JP4663249B2 - Magnetic steel sheet for iron core - Google Patents

Description

  The present invention relates to an electromagnetic steel sheet used for electrical equipment such as an iron core with reduced noise.

  Iron cores such as transformers and rotating machines are manufactured by cutting and stacking magnetic steel sheets into a predetermined shape, or slitting them into a predetermined width and winding them in a spiral shape. In addition to high efficiency for energy saving, iron cores are highly demanded for low noise. Particularly in large iron cores such as transformers, noise due to magnetostriction due to magnetization is a problem. For example, Patent Document 1 discloses a method for reducing magnetostriction of a magnetic steel sheet.

  Moreover, as a noise reduction method by the structure of an iron core, Patent Document 2 proposes a method of manufacturing an iron core in which noise is reduced by pouring adhesive resin after laminating magnetic steel sheets in which grooves are formed in advance.

Japanese Patent Laid-Open No. 11-87122 JP 2003-77747 A

  As a result of investigating the technique disclosed in Patent Document 2, the present inventors have found that the noise characteristics vary greatly depending on the shape of the grooves of the electromagnetic steel sheet, and the noise is limited while limiting the influence on the characteristics such as iron loss. The present invention provides a noise suppressing laminated iron core electrical steel sheet having an optimum groove shape by examining the groove shape to be reduced.

The present invention has been made on the basis of the above findings and has the following configuration.
(1) A steel sheet having a groove that leads to the end on one or both surfaces, and is laminated so that surfaces without grooves do not overlap each other, and then used for manufacturing an iron core by infiltrating a resin into the groove. The groove spacing is 2 to 15 mm, the groove forming angle is 85 ° or less with respect to the magnetization direction of the steel sheet, and the maximum gap formed around the grooves when the electromagnetic steel sheets are laminated A magnetic steel sheet for iron cores having a depth of 5 μm or more and 15% or less of the thickness of the steel sheet, and a maximum width of 0.070 to 0.50 times the groove interval.

  By producing an iron core using the electromagnetic steel sheet of the present invention and impregnating with a resin, noise due to magnetostriction can be reduced.

  The present invention is described in detail below.

  The electrical steel sheet used in the present invention has a groove that leads to the end on one or both sides of a known directional electrical steel sheet or non-oriented electrical steel sheet. The thickness of these electromagnetic steel sheets is generally 0.15 to 0.50 mm. After this electromagnetic steel sheet is cut into a predetermined shape or punched and laminated, a resin is infiltrated into a gap formed around the groove opened at the end to produce an iron core.

  The present inventors have found that the noise characteristics of the manufactured iron core vary depending on the size of the gap and the direction of the groove. The conditions will be described below.

  FIG. 1 is a schematic diagram showing an example of the electrical steel sheet of the present invention. In FIG. 1, (a) is an example in which grooves are formed on the surface of a steel sheet by a pressing method, and (b) is an example in which grooves are formed by an etching method. FIG. 2 is a schematic view of a cross section when this steel plate is cut out to a predetermined size and superposed so that there is a groove on one of the superposed steel plates. Reference numeral 2 in FIG. 2 denotes a groove, and the iron core targeted by the present invention is characterized in that a resin is infiltrated into this groove after the steel plates are laminated. Here, reference numeral 3 is the depth of the gap, reference numeral 4 is the groove interval, and reference numeral 5 is the maximum width of the gap.

  First, the depth of the gap, that is, the size of the gap in the thickness direction of the steel plate needs to be 5 μm or more. If the gap depth is smaller than 5 μm, it becomes difficult for the resin to pass through, and since the absolute amount of the resin is small, the noise reduction effect is not sufficient. The upper limit is not particularly defined, but if it exceeds 30 μm, it may be unfavorable because the magnetic properties are deteriorated particularly in a thin steel plate. A more desirable groove depth is in the range of approximately 5 to 15% of the plate thickness of the steel plate.

  Next, the maximum width of the gap is 0.070 to 0.50 times the groove interval. If the width of the gap is less than 0.070 times the gap between the grooves, the adhesive force and noise suppression force by the resin are not sufficient. On the other hand, if it exceeds 0.50 times, the dent will bend due to external force, and the resin will instead be difficult to penetrate or adversely affect the magnetic properties.

  The distance between the grooves is preferably 2 to 15 mm in view of the relationship with the size of the gap. If it is less than 2 mm, the size of the groove has to be relatively small, it becomes difficult for the resin to penetrate, and since the absolute amount of the resin is small, the noise reduction effect is not sufficient. On the other hand, if it exceeds 15 mm, the width of the resin becomes relatively small, and the adhesive force and noise suppression force are not sufficient.

  Various known groove forming methods may be used as the method for forming the grooves in the electromagnetic steel sheet. Especially for grain-oriented electrical steel sheets, groove forming methods for improving magnetic properties include mechanical methods of applying blades with rolls and presses, physical methods of scribing with lasers and plasma, and linear resist formation. Although a method of etching after mechanically or physically scratching the insulating coating is disclosed, these techniques can be applied. Alternatively, a method of forming a groove when punching into a predetermined shape or after punching may be used. Further, the step of forming the groove may be after the completion of the steel plate product or during the steel plate product manufacturing process.

  In addition, the mechanical method and the method using heat are deformed to the periphery of the groove. However, in a range where the influence on the magnetic characteristics is small, by providing such a deformation, the size of the groove itself can be reduced. However, the gap can be formed large, which is advantageous in terms of magnetic flux density and space factor.

  The groove forming angle is preferably 85 ° or less with respect to the magnetization direction of the steel sheet. Since magnetostriction is the expansion and contraction of the iron core parallel to the magnetization direction, the magnetostriction suppressing effect by the resin increases as the groove direction becomes closer to the magnetization direction. However, in this case, in the grain-oriented electrical steel sheet, the effect of improving the magnetic properties by the groove is hardly obtained. On the other hand, when the groove direction is substantially perpendicular to the magnetization direction by exceeding 85 °, the magnetostriction suppressing effect by the resin is reduced. Further, in the case of a structure such as a three-phase core, for example, as shown in FIGS. 3B and 3C, if it is substantially perpendicular to or parallel to the magnetization direction, X in the figure from the end face of the core. The distance to the part becomes very long, and it takes a long time for the resin to permeate. However, as shown in (a), it is possible to reduce the part far from the end face by setting it to approximately 45 °. It is possible to shorten the work time required for resin penetration.

  When manufacturing an iron core using the steel plate of the present invention, the resin is infiltrated from the gap after lamination. The type of the resin is not particularly limited, but a resin that can be adjusted to have a low viscosity and a liquid whose drying speed is too high is not preferable. Having adhesiveness after drying is preferable for suppressing magnetostriction because the steel plates can be bonded to each other. Examples include an acrylic resin emulsion, an epoxy resin, and an aqueous resin.

  These resins are applied to the end face of the iron core by means such as brushing, spraying or dripping. Alternatively, an iron core may be impregnated in a tank filled with resin. After coating or impregnation, let it air dry. Depending on the resin, the iron core may be dried at a high temperature, or may be annealed to remove distortion.

  Grooves are formed on a grain-oriented electrical steel sheet with a thickness of 0.35 mm by the means shown in Table 1, and then a three-phase transformer of 300 mm x 300 mm and a laminated thickness of 50 mm is manufactured, impregnated in a tank filled with aqueous resin, and taken out It was naturally dried to make an iron core, and a conductor was wound around it to make a transformer. As for the shape of the gap, the end face of the iron core after resin impregnation was polished and transferred, and the dimensions were confirmed. Noise characteristics were excited at 50 Hz and 1.5 T, and measured with a noise measuring device.

  Here, in the pressing method, pressing was performed with a pressing force having a depth shown in Table 1 using a blade with a plurality of blades having a blade edge angle of 30 ° in parallel with an interval of 5 mm. In the scribing method, a needle having a tip angle of 20 ° was used to move the plate in the direction of the plate surface while pressing with a force having a depth shown in Table 1. In the etching method, a film having a width shown in Table 1 was irradiated with a laser, and then electrolysis was performed in an alkaline solution until a groove having a depth shown in Table 1 was obtained. In any case, an insulating film mainly composed of phosphoric acid was applied after the treatment.

  As shown in Table 1, the transformer according to the conditions of the present invention was able to reduce noise characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram of the electromagnetic steel plate for iron cores by this invention, (a) is an example which formed the groove | channel on the steel plate surface by the press method, (b) is a figure which shows the example which formed the groove | channel by the etching method. (A), (b) is the schematic diagram of a cross section when the steel plate of FIG. 1 is cut out to predetermined size, and it overlap | superposed so that it may have a groove | channel on one side among the steel plates to overlap. (A) is an example in which the groove direction applied to the electrical steel sheet is 45 °, (b) is an example in which the groove direction is perpendicular to the magnetization direction, and (c) is a three-phase iron when the groove direction is parallel to the magnetization direction. It is a figure which shows the example of a heart.

Claims (1)

In the steel sheet having a groove that leads to the end on one or both surfaces, after laminating so that the surfaces without grooves do not overlap each other, the electromagnetic steel sheet used for manufacturing the iron core by infiltrating the resin into the groove, The groove interval is 2 to 15 mm, the formation angle of the groove is 85 ° or less with respect to the magnetization direction of the steel sheet, and the maximum depth of the gap formed around the groove when the electromagnetic steel sheets are laminated is A magnetic steel sheet for an iron core, characterized by being 5 μm or more and 15% or less of the thickness of the steel sheet and having a maximum width of 0.070 to 0.50 times the groove interval.

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