JP2011193622A - Laminate core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate core capable of solving a problem occurring when an insulating film contains phosphate or chromate. <P>SOLUTION: The laminate core 1 includes laminated electromagnetic steel plates 11, and insulating films 12 are formed between the electromagnetic steel plates 11 respectively. Since the insulating film 12 is made of at least any one of DLC (diamond-like carbon) and fullerene, it can be formed at a low temperature. A step of cooling the insulating film 12 can be remarkably reduced. Since the insulating film 12 contain no hazardous material, it is never limited in use from a view of environmental impact. Since the insulating film 12 has good heat conductivity, heat conduction in a laminate direction is good when a motor having a built-in laminate core is used. When the electromagnetic steel plate 11 is punched, punching processability is good. The insulating film 12 has good substrate followability. When an electromagnetic coil is wound around the laminate core 1, an insulating coating of the electromagnetic coil can be free from damage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laminated core in which electromagnetic steel sheets are laminated with an insulating film interposed therebetween, and more particularly to an improvement of the insulating film.

  The laminated core is used, for example, as a motor core material. In the formation of the laminated core, an insulating film is coated on the surface of the electromagnetic steel sheet, a punching process is performed on the electromagnetic steel sheet coated with the insulating film, and the processed electromagnetic steel sheets are stacked.

  Insulating films are required to have various properties such as corrosion resistance, heat resistance, slipperiness, adhesion to electromagnetic steel sheets, punchability, weldability, and film flexibility, in addition to insulating properties to suppress eddy currents. For example, when a grain-oriented electrical steel sheet is used as the electrical steel sheet, the insulating film is composed of an underlayer (forsterite layer) and a phosphate layer.

In this case, the base layer is generated by a chemical reaction between MgO applied for preventing adhesion between steel plates and SiO ₂ formed in the decarburization annealing process during finish annealing, and the phosphate layer is formed of phosphoric acid. It is formed by applying a liquid mainly composed of salt or the like to a grain-oriented electrical steel sheet and baking the applied liquid. In particular, when improving magnetic properties by facilitating the domain wall movement by applying tension to the steel sheet, phosphate contains chromate or the like in order to give high tension to the insulating film (for example, patent document) 1, 2).

  In addition, when a non-oriented electrical steel sheet is used as the electrical steel sheet, an organic-inorganic insulating film is used from the viewpoint of punchability and heat resistance, and the inorganic composition is the same as the directional electrical steel sheet. Chromate and phosphate are used.

JP 48-39338 A Japanese Patent Laid-Open No. 61-41778

  However, in forming an insulating film containing phosphate, chromate, etc., drying or baking is performed at a high temperature of 200 ° C. to 500 ° C., so a large drying furnace and a large production facility are required, and productivity is increased. bad. In addition, the use of a compound containing chromium or the like is restricted by, for example, the RoHS directive from the viewpoint of environmental load. Furthermore, since the insulating film between the electromagnetic steel sheets is made of ceramics, the thermal conductivity in the stacking direction is poor and it is difficult to dissipate heat.

  In addition, when the grain-oriented electrical steel sheet is used, the base layer formed during finish annealing is made of ceramics and is a very hard layer. For this reason, the life of the mold used for the punching process becomes very short as compared with the case where the non-oriented electrical steel sheet is used. In addition, when a grain-oriented electrical steel sheet is used, a high tension is required for the insulating film in order to apply tension to the steel sheet, but since the conventional insulating film is made of ceramics, there is a limit to the application of tension.

  Therefore, an object of this invention is to provide the laminated core which can eliminate the said problem produced when an insulating film contains a phosphate, chromate, etc.

  The laminated core of the present invention includes laminated electromagnetic steel sheets and an insulating film formed between the electromagnetic steel sheets, and the insulating film is made of at least one of DLC and fullerene.

  In the laminated core of the present invention, since the insulating film is composed of at least one of DLC and fullerene, the insulating film can be formed at a low temperature, and a large facility for that purpose is not required. In addition, since the cooling process during the formation of the insulating film can be greatly reduced, productivity can be improved. In addition, since the insulating film is mainly composed of carbon and does not contain harmful substances, its use is not limited from the viewpoint of environmental burden.

  In addition, since the above-described material of the insulating film has good thermal conductivity, when a motor incorporating a laminated core is used, the thermal conductivity in the laminating direction is improved and heat dissipation can be easily performed. In the production of a laminated core, when punching a magnetic steel sheet after forming an insulating film on the magnetic steel sheet, the punching workability is good. Thereby, it is possible to extend the life of the die for punching, and it is possible to reduce the burrs of the press parts generated in the punching. In addition, since the substrate followability of the insulating film is good, it is possible to prevent the occurrence of cracks that cause a decrease in the insulating property of the insulating film when tension is applied to the steel sheet.

  Furthermore, since the surfaces of the electromagnetic steel sheets at both ends in the vertical direction of the laminated core are covered with an insulating film, when the electromagnetic coil is wound around the laminated core, the insulation coating of the electromagnetic coil can be prevented from being broken.

  Various configurations can be used for the laminated core of the present invention. For example, it is possible to use a mode in which another insulating film made of the same material as the above insulating film is formed on a portion where the electromagnetic steel sheet on which the winding of the electromagnetic coil is exposed (for example, an end of the electromagnetic steel sheet). . In this aspect, since the horizontal direction edge part of an electromagnetic steel plate can be coat | covered with another insulating film, destruction of the insulation coating of an electromagnetic coil can be prevented effectively.

  Moreover, the aspect which has a cross-sectional shape that a horizontal direction length becomes small as it goes to an edge part from a center part in a lamination direction can be used. In this aspect, the edge of the horizontal end portion of the electromagnetic steel sheet can be covered with the insulating film, so that the edge portion that contacts the electromagnetic coil at the time of winding can be covered with the insulating film. Breakage of the insulation coating can be effectively prevented. Furthermore, the aspect whose amount of hydrogen contained in DLC is 20 at% or more can be used. In this aspect, since the substrate followability of the insulating film is further improved, it is possible to effectively prevent the occurrence of cracks that cause a decrease in the insulating property of the insulating film when tension is applied to the steel sheet.

  According to the laminated core of the present invention, it is possible to easily dissipate heat when the motor is used, and to prevent the insulation coating of the electromagnetic coil from being broken. In the production of the laminated core, a large facility is not required for forming the insulating film, and productivity can be improved. From the viewpoint of environmental load, the use of the insulating film material is not limited. It is possible to extend the service life of the die for punching, reduce the burrs of the press parts generated in the punching process, and prevent cracks that cause a decrease in insulation of the insulating film when tension is applied to the steel sheet. Occurrence can be prevented.

It is a sectional side view showing the schematic structure of the laminated core which concerns on one Embodiment of this invention. It is a sectional side view showing the schematic structure of the modification of the laminated core which concerns on one Embodiment of this invention. It is a top view showing schematic structure of the electromagnetic steel plate before stamping.

(1) First Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view showing a schematic configuration of a laminated core 1 according to an embodiment of the present invention. The laminated core 1 includes laminated electromagnetic steel plates 11, and an insulating film 12 is formed between the electromagnetic steel plates 11. In addition, it is preferable that an insulating film made of the same material as the insulating film 12 is formed on a portion where the electromagnetic steel plate 11 is exposed (for example, an end of the electromagnetic steel plate 11).

  The insulating film 12 is made of at least one of DLC (Diamond-Like Carbon) and fullerene. Specifically, the insulating film 12 is a fullerene film, a DLC film, a fullerene-containing DLC film, or a mixed film of these films.

Fullerene is a fullerene simple substance, a chemically modified fullerene simple substance subjected to chemical modification, or a mixture thereof. The fullerene itself, for example _{C 60, C 70, C 76} , C 78, C 82, C 84, C 90, C 94, C alone or a mixture thereof, such as ₉₆ and the like. In this case, the fullerene simple substance may contain C ₁₀₀ or higher order fullerene. Examples of the chemically modified fullerene simple substance include simple substances such as C ₆₀ F _x or a mixture thereof. When using the fullerene rolling operation, it is preferable to use C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ , C ₉₀ , C ₉₄ , C ₉₆ as the fullerene.

  When a fullerene film is used as the insulating film 12, the film thickness of the fullerene film is not particularly limited, but is preferably in the range of 0.7 nm to 100 μm. When the film thickness is less than 0.7 nm, it becomes not more than the diameter of the minimum fullerene molecule, so that good insulation cannot be obtained. When the film thickness is more than 100 μm, the fullerene molecules aggregate and form aggregates, so that a uniform film cannot be obtained.

  When a fullerene-containing DLC film is used as the insulating film 12, the film thickness of the fullerene-containing DLC film is not particularly limited, but is preferably in the range of 1 nm to 100 μm. When the film thickness is less than 1 nm, a uniform film cannot be formed, and good insulating properties cannot be obtained. When the film thickness is more than 100 μm, the electrical insulation of the electrical steel sheet on which the fullerene-containing DLC film is formed becomes high, electrons generated during the CVD film formation stay, and the potential around the electrical steel sheet 11 becomes unstable. The film quality becomes non-uniform.

  Since the DLC film and the fullerene-containing DLC film can have high thermal conductivity of, for example, about 30 W / (m · K), thermal diffusion in the stacking direction of the stacked core 1 is increased. Since the fullerene film has a very thin film thickness for obtaining a desired insulating property, the influence of being interposed between the electromagnetic steel sheets 11 is small. Thereby, heat radiation can be easily performed when the motor to which the laminated core 1 is applied is used.

  A method for manufacturing the laminated core 1 having the above configuration will be described. First, the electromagnetic steel sheet 11 is prepared. The electrical steel sheet 11 is an electrical steel sheet having a predetermined thickness formed by steelmaking, hot rolling, annealing, cold rolling, and annealing (further annealing is performed as necessary). Next, the insulating film 12 is uniformly formed on the surface of the electromagnetic steel sheet 11.

  When a fullerene film is used as the insulating film 12, the fullerene is coated on the surface of the electromagnetic steel sheet 11 by dissolving the fullerene in a solvent that easily volatilizes to produce a fullerene solution and uniformly coating the surface of the electromagnetic steel sheet 11. The solvent is not particularly limited, but is a nonpolar solvent or a benzene solvent in which fullerene is dissolved. When a nonpolar solvent is used, the nonpolar solvent may be mixed with a highly volatile polar solvent after the fullerene is dissolved in the nonpolar solvent. When chemically modified fullerene is used as the fullerene, the non-polarity / polarity of the solvent is not limited because the chemically modified fullerene is dissolved in a polar solvent.

  Examples of the coating method of the fullerene solution include a spray method, a splashing method, and a dropping method. In this case, an organic substance such as acrylic or epoxy may be mixed with the fullerene solution in order to improve the adhesion. In this method, the insulating film 12 can be formed at room temperature by using a highly volatile solvent.

  When a mixed film of a fullerene film and a DLC film is used as the insulating film 12, the above-described coating method for the fullerene film is combined with the following coating method for the DLC film. For DLC film coating, the method is not particularly limited, but thermal CVD method, plasma CVD method, photo CVD method, catalytic chemical vapor deposition (Cat-CVD), atmospheric pressure CVD, vacuum deposition method , Ion plating (direct current excitation, high frequency excitation), sputtering method (bipolar sputtering, magnetron sputtering, ECR sputtering), laser ablation method, ion beam deposition, ion implantation method and the like. Among these methods, plasma CVD and atmospheric pressure CVD capable of three-dimensional film formation at a low temperature are preferable. For example, when using the case of plasma CVD, the insulating film 12 can be formed at a low temperature of about 40 ° C. to 100 ° C.

  When a fullerene-containing DLC film is used as the insulating film 12, fullerene is contained in the DLC raw material or target in the above-described coating method of the DLC film. Thereby, a fullerene-containing DLC film is obtained.

  The insulating film 12 is uniformly formed on the surface of the electromagnetic steel sheet 11 by the above method. Further, the insulating film 12 can be formed at a low temperature, and a large facility for that purpose is not required. In addition, since the cooling process during the formation of the insulating film 12 can be significantly reduced, productivity can be improved. Further, the insulating film 12 is made of at least one of DLC and fullerene, and mainly contains carbon, so there is no environmental impact.

  Next, a punching process is performed on a predetermined region X (FIG. 3) of the electromagnetic steel sheet 11. Here, since DLC used as the material of the insulating film 12 is excellent in slipperiness and fullerene is excellent in lubricity, the fullerene film, the DLC film, the fullerene-containing DLC film that is the insulating film 12, or a mixed film of these films, The punching processability can be improved. Thereby, it is possible to extend the life of the die for punching, and it is possible to reduce the burrs of the press parts generated in the punching. Moreover, in a DLC film or a fullerene containing DLC film, it can follow the electromagnetic steel plate 11 by a fine crack producing. Further, in the fullerene film, fullerene molecules are intermolecular bonds, and therefore followability to the electromagnetic steel sheet 11 is good. Therefore, it is possible to prevent the occurrence of cracks that cause a decrease in the insulating properties of the insulating film when tension is applied to the electromagnetic steel sheet 11.

  In particular, when the amount of hydrogen contained in the DLC film or the fullerene-containing DLC film is 20 at% or more, the followability of the insulating film 12 to the electromagnetic steel sheet 11 is improved, so that the occurrence of cracks is effectively prevented. Obtainable. In the punching process, the punching jig used for the punching process may be coated with an insulating film made of the same material as the insulating film 12.

  Next, the laminated core 1 is obtained by laminating the electromagnetic steel plates 11 on which the insulating film 12 is formed and fixing the laminated electromagnetic steel plates 11. Subsequently, an electromagnetic coil (not shown) is wound around the laminated core 1.

  Here, since the surface of the electromagnetic steel sheet 11 located on the upper surface and the lower surface of the laminated core 1 is covered with the insulating film 12 having good sliding property or lubricity, the insulation coating of the electromagnetic coil in contact therewith is prevented from being broken. can do. In particular, by forming an insulating film made of the same material as that of the insulating film 12 in a portion where the electromagnetic steel plate 11 is exposed in the side surface portion of the laminated core 1, it is possible to prevent the insulation coating of the electromagnetic coil contacting the same from being destroyed. Can do.

  In this embodiment, it is possible to easily dissipate heat when the motor is used, and to prevent the insulation coating 12 of the electromagnetic coil from being broken. Further, in the manufacture of the laminated core 1, a large facility is not required for forming the insulating film 12, and productivity can be improved. From the viewpoint of environmental load, the use of the material of the insulating film 12 is not limited. In addition, the life of the die for punching can be extended. Further, it is possible to reduce the burrs of the pressed parts generated in the punching process, and it is possible to prevent the occurrence of cracks that cause a decrease in insulating properties of the insulating film 12 when tension is applied to the steel sheet.

(2) Second Embodiment FIG. 2 is a side sectional view showing a schematic configuration of a laminated core 2 according to a second embodiment of the present invention. The laminated core 2 is different from the laminated core 1 only in that it has a cross-sectional shape such that the length in the horizontal direction decreases from the center to the end in the lamination direction.

  In the punching process of the electromagnetic steel sheet 11, various sizes of the electromagnetic steel sheet 11 used for the laminated core 2 are obtained by appropriately changing the size of the predetermined region X shown in FIG. 3. In the electromagnetic steel sheet 11 located in the center part of the laminated core 2, the insulating film 12 may be formed on the upper surface and the lower surface.

  In the laminated core 2, in addition to the above effects of the laminated core 1 of the first embodiment, the following effects can be obtained. In the laminated core 2, since the edge of the horizontal direction edge part of the electromagnetic steel plate 11 can be coat | covered with the insulating film 12, the edge part which an electromagnetic coil contacts can be coat | covered with the insulating film 12 at the time of winding. As a result, it is possible to effectively prevent the insulation coating of the electromagnetic coil from being broken.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to specific examples. In the examples, the characteristics of electrical steel sheets covered with various insulating films were examined.

(1) Sample preparation In samples 11 to 13 and comparative sample 11, a non-oriented electrical steel sheet (material: Fe-Si) having a length of 0.35 mm was used as the electrical steel sheet. In the preparation of Sample 11, a Si underlayer was coated on the surface of the magnetic steel sheet by sputtering in order to improve adhesion, and then a DLC film (film thickness of about 1 μm) was formed by plasma CVD.

In the preparation of Sample 12, fullerene composed of a mixture of C ₆₀ and C ₇₀ was dissolved in 1,24-trimethylbenzene (solubility 17.9 mg / ml), and then the solution was mixed with highly volatile ethanol. A fixed amount of fullerene solvent was prepared. Fullerene solvent was applied to the electrical steel sheet and a fullerene film was formed by natural drying. In the preparation of Sample 13, after a DLC film was formed on the electromagnetic steel sheet by the same method as Sample 11, a fullerene film was formed by the same method as Sample 12. As the comparative sample 11, an electrical steel sheet coated with a phosphate film by a conventional technique was used. The insulating film formation temperatures of Samples 11 to 13 and Comparative Sample 11 are shown in Table 1.

(2) Sample characteristics Samples 11 to 13 and comparative sample 11 were examined for insulation resistivity, thermal conductivity, static friction coefficient, and flexibility (followability) of the insulating film. In the insulation resistivity measurement, a four-probe method was used as a measurement target of the insulating film surface of the steel plate. In thermal conductivity measurement, three samples processed to have a diameter of 10 mm for each sample were laminated to obtain a laminate (total thickness 1.05 mm), and the thermal conductivity of the laminate was obtained by the laser flash method. It was. In the static friction coefficient measurement, the static friction coefficient of the insulating film of the electromagnetic steel sheet was obtained using a 10 mm × 10 mm cemented carbide piece using an inclined type static friction measuring machine. In this case, the weight of the contact was set to 200 g, and the measurement time was set to about 10 seconds. The flexibility of the insulating film was obtained by bending the electromagnetic steel sheet by 90 °, obtaining the degree of deterioration of the insulating film at the edge of the electromagnetic steel sheet at that time, and determining the presence or absence of cracks. The results are shown in Table 1. In Table 1, the data of each characteristic is shown using the data of the sample 11 as a reference (= 1). Table 1 also shows the formation temperature of the insulating film.

  As can be seen from Table 1, the samples 11 to 13 were improved in comparison with those of the comparative sample 11 in terms of thermal conductivity and flexibility of the insulating film. As a result, it was confirmed that the thermal conductivity and the flexibility of the insulating film can be improved by using an insulating film made of at least one of DLC and fullerene as the insulating film of the electromagnetic steel sheet. Moreover, it confirmed that the samples 11-13 became small compared with the thing of the comparative sample 11 about the static friction coefficient of an insulating film. As a result, it was confirmed that the punching workability can be improved by using an insulating film made of at least one of DLC and fullerene as the insulating film of the electromagnetic steel sheet.

  1, 2 ... laminated core, 11 ... electromagnetic steel sheet, 12 ... insulating film

Claims (6)

Laminated electrical steel sheets,
An insulating film formed between the electromagnetic steel plates,
The laminated core is characterized in that the insulating film is made of at least one of DLC and fullerene. The laminated core according to claim 1, wherein another insulating film made of the same material as the insulating film is formed at an end of the electromagnetic steel sheet.   3. The laminated core according to claim 1, wherein the laminated core has a cross-sectional shape such that a length in a horizontal direction becomes smaller from a center portion toward an end portion in the lamination direction.   The laminated core according to any one of claims 1 to 3, wherein the amount of hydrogen contained in the DLC is 20 at% or more.   The laminated core according to claim 1, wherein the insulating film is a fullerene film, and the film thickness thereof is in a range of 0.7 nm to 100 μm.   The laminated core according to any one of claims 1 to 4, wherein the insulating film is a fullerene-containing DLC film, and the film thickness thereof is in a range of 1 nm to 100 µm.

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