Patent Publication Number: US-2017352466-A1

Title: Laminated Iron Core Structure and Transformer Including the Same

Description:
TECHNICAL FIELD 
     The present invention relates to a laminated iron core structure and a transformer including the same. 
     BACKGROUND ART 
     Iron core structures of a transformer are roughly classified into a wound iron core and a laminated iron core. The wound iron core is chiefly adopted for a distribution transformer, and the laminated iron core is adopted for small transformer for power electronics and a large-capacity transformer which is larger than the distribution transformer. As iron core materials for transformers, there are a silicon steel sheet and an amorphous alloy. An amorphous transformer adopting the amorphous alloy as the iron core material is known as the transformer which has a smaller loss and better energy consumption efficiency than the silicon steel sheet transformer adopting the silicon steel sheet as the iron core material. 
     The large-capacity transformer using the amorphous alloy having good energy consumption efficiency is required in recent years, however, it is difficult to manufacture the transformer using the laminated iron core structure due to the following reasons. First, an iron core having a larger cross-sectional area is required for the large-capacity transformer, and the width of the iron core and the thickness of lamination are extremely larger than those of a normal iron core for the transformer. However, the amorphous alloy is the material having a thickness of approximately 1/10 of the silicon steel sheet, and the number of laminations will be enormous for manufacturing the iron core used for the large-capacity transformer. Additionally, a material width of the amorphous alloy which can be manufactured is smaller than a material width necessary for the iron core of the large-capacity transformer, and variations in material widths to be supplied are small in the present technique. Accordingly, there is a case where the material width of the iron core is not sufficient for manufacturing the large-capacity transformer by using the amorphous material. 
     There exists JP-A-2012-138469 (Patent Literature 1) as a background art in the technical field. This publication discloses that “an amorphous core is made to be self-supported in good condition while improving hang-down at the corner of the core due to its own weight when the core is self-supported, and work efficiency is enhanced by assembling the core and a coil smoothly. In an amorphous transformer including an amorphous core formed of an amorphous material and made to be self-supported substantially vertically in a state of being designated by a core supporting member while placing a lap part at the top, and a coil inserted into the amorphous core, the core supporting member is formed by the core supporting member for supporting a side surface of the amorphous core and a corner supporting member for supporting the corner of the core so as to be integrated with each other, and the core supporting member is placed substantially vertically along at least one side surface of the core.”, however, a method for making the large-capacity transformer is not disclosed. 
     Also, JP-A-11-186082 (Patent Literature 2) discloses that “a method of manufacturing an amorphous laminated iron core is proposed, in which work efficiency is improved by enabling a unit copolymer formed of copolymer of the ribbon of an amorphous magnetic alloy foil to be made easily. A unit copolymer  10  is formed by cutting a strip copolymer made of plural strips of the amorphous magnetic alloy foil overlapping one another into a specified length. A laminated block  11  of unit copolymers is formed by laminating the unit copolymers which are sequentially formed while shifting positions in a length direction. A leg portion and a yoke portion of the laminated iron core are formed by taking the unit copolymers  10  forming the laminated block  11  sequentially from the top and laminating them on a work bench.”, which discloses the structure of the laminated iron core made of the amorphous alloy, however, the iron core in the description is also one formed by laminating iron core materials with the single width, and it is difficult to manufacture the iron core for the large-capacity transformer. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP-A-2012-138469 
     Patent Literature 2: JP-A-11-186082 
     SUMMARY OF INVENTION 
     Technical Problem 
     It has been difficult to manufacture a large-capacity transformer with a laminated iron core structure by using an amorphous alloy easily. 
     Solution to Problem 
     In order to solve the above problems, for example, structures described in claims are adopted. The present application includes plural means for solving the above problems, and an example thereof is cited as follows: A laminated iron core structure according to the invention includes a laminated iron core configured by aligning a plurality of laminated iron core blocks each configured by laminating iron core materials in a direction different from a lamination direction, a first frame extending along an outer periphery of the laminated iron core and a partition plate arranged between the plurality of laminated iron core blocks. 
     Advantageous Effects of Invention 
     The large-capacity transformer of the laminated iron core structure can be easily manufactured by using the amorphous alloy. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view of an inside of a transformer according to a first embodiment of the invention. 
         FIG. 2  is a side view of the inside of the transformer according to the first embodiment of the invention. 
         FIG. 3 a    is a perspective view of a laminated body of an iron core used for the transformer according to the first embodiment of the invention. 
         FIG. 3 b    is a front view of a first laminated block of the iron core used for the transformer according to the first embodiment of the invention. 
         FIG. 3 c    is a front view of a second laminated block of the iron core used for the transformer according to the first embodiment of the invention. 
         FIG. 3 d    is a front view of a laminated body of the first laminated block and the second laminated block of the iron core used for transformer according to the first embodiment of the invention. 
         FIG. 4  is a cross-sectional view of a leg portion of the iron core used for transformer according to the first embodiment of the invention. 
         FIG. 5  is a cross-sectional view of a yoke portion of the iron core used for transformer according to the first embodiment of the invention. 
         FIG. 6  is a perspective view of an iron core fixing metal fitting according to the first embodiment of the invention. 
         FIG. 7  is a front view of a laminated body of the iron core according to a second embodiment. 
         FIG. 8  is a front view of a laminated body of the iron core according to a third embodiment. 
         FIG. 9  is a front view of a laminated body of the iron core according to a fourth embodiment. 
         FIG. 10  is a cross-sectional view of a leg portion of the iron core according to a fifth embodiment. 
         FIG. 11  is a cross-sectional view of a leg portion of the iron core according to a sixth embodiment. 
         FIG. 12  is a cross-sectional view of a leg portion of the iron core according to a seventh embodiment. 
         FIG. 13  is a cross-sectional view of a yoke portion of the iron core according to an eighth embodiment. 
         FIG. 14  is a cross-sectional view of a leg portion of the iron core according to a ninth embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the invention will be explained by respective embodiments with reference to the drawings. 
     Embodiment 1 
     Embodiment 1 of the invention will be explained with reference to  FIG. 1  to  FIG. 6 . An inner structure of a transformer according to Embodiment 1 will be explained in  FIG. 1  and  FIG. 2 .  FIG. 1  is a front view and  FIG. 2  is a side view. The inner structure of the transformer according to the invention includes an iron core  100 , a coil  200 , upper fasteners  300 , lower fasteners  400 , a core fixing metal fitting  500 , fastener fastening studs  600  and a base  700 . The core fixing metal fitting  500  is a tubular member having a square shape in cross section which surrounds a circumference of the laminated iron core  100 , which is arranged so as to penetrate the coil  200 . The upper fasteners  300  and the lower fasteners  400  are fastened by the fastener fastening studs  600 , thereby fixing the iron core  100  arranged in the core fixing metal fitting  500 . The core fixing metal fitting  500  is further fixed to the upper fasteners  300  and the lower fasteners  400  by bolts. The lower fasteners  400  are fixed to the base  700  arranged at the bottom by bolts. 
       FIG. 3( a )  is a perspective view of the iron core  100  depicted in  FIG. 1 , which shows a state where the coil  200 , the upper fasteners  300 , the lower fasteners  400 , the core fixing metal fitting  500  and the base  700  are removed from  FIG. 1 . The iron core  100  is formed by aligning an iron core material  107  and an iron core material  108  with a prescribed width in parallel, in which plural plate-shaped iron core materials are laminated in a Y-axis direction. In the case where a thin material such as an amorphous alloy material is used as the iron core material, for example, approximately 15 to 20 pieces of materials are set as one lamination unit (hereinafter expressed as a laminated block) and plural number of laminated blocks are further laminated to form the iron core  100 . A material boundary partition  900  which is a plate-shaped member is sandwiched between the iron core material  107  and the iron core material  108  and between the iron core material  110  and the iron core material  111 . The iron core  100  is formed by laminating plural laminated blocks, and a lamination surface partition  800  which is a plate-shaped member is sandwiched at part between the laminated blocks. The details of the material boundary partition  900  and the lamination surface partition  800  will be described later with reference to  FIG. 4 . 
     Explaining the structure of the iron core  100 , first, nomenclature of respective portions will be explained. The iron core  100  includes a core portion (a periphery of a cross section A) which is part of three iron core legs and arranged inside the coil  200  in  FIGS. 1 and 2 , and a yoke portion (periphery of a cross section B) connecting three iron core legs and fixed by the upper fasteners  300  or the lower fasteners  400 . In the embodiment, the core portion indicates part of the iron core members  107 ,  108 ,  110  and  111 , which is arranged inside the coil  200 , and the yoke portion indicates iron core members  101 ,  102 ,  104  and  105 . The details of the core portion will be described with reference to  FIG. 4  and the details of the yoke portion will be described with reference to  FIG. 5  later. 
       FIG. 3( b )  is a front view of a first laminated block, and  FIG. 3( c )  is a front view of a second laminated block which is laminated adjacent to the first laminated block.  FIG. 3( d )  is a front view showing a state where  FIG. 3( b )  and FIG.  3 ( c ) overlap each other. Although the material boundary partition  900  is omitted for simplifying the explanation in respective drawings, the material boundary partition  900  is inserted between the iron core materials  101  and  102 , between  104  and  105  and between  110  and  111 , respectively. 
     Each laminated block is formed by laminating, for example, approximately 15 to 20 pieces of same iron core materials in the depth direction of the paper though not shown in  FIGS. 3( b ) and ( c )  as they are front views.  FIGS. 3( b ) and ( c )  have a relationship of facing each other with their backs. The iron core  100  in  FIG. 3( a )  is formed by laminating plural pieces of  FIG. 3( d )  and inserting the material boundary partition  800  and the lamination surface partition  900 , which is, namely, formed by alternately laminating the laminated block of  FIG. 3( b )  and the laminated block of  FIG. 3( c ) . 
     When respective first and second laminated blocks are laminated so that a boundary portion between the iron core material  110  and the iron core material  111  makes a straight line as well as the first and second laminated blocks are laminated so that a boundary portion between the iron core material  107  and the iron core material  108  makes a straight line as shown in  FIG. 3( d ) , the first and second laminated blocks are shifted by a given width at a position of joints  115 . The shift amount is determined in accordance with the shape of the central iron core leg, which is, for example, approximately ten-odd millimeters and can be arbitrarily selected by design specifications. In the embodiment, the joint  115  between the iron core material  111  of the central iron core leg and the iron core material  101  of the yoke portion are formed so as to be 45 degrees with respect to a direction (Z-axis direction) in which the iron core material  111  of the central iron core leg extends, however, the angle of the joint  115  is not limited to this. In the case of the embodiment, two iron core materials  101  arranged right and left with the iron core material  110  and the iron core material  111  forming the central iron core leg interposed therebetween are made to be two members which are divided by the existence of the central iron core leg. However, in the case where the joint  115  is formed, for example, at an angle of 60 degrees with respect to the direction (Z-axis direction) in which the iron core material  111  extends, these iron core materials  101  are not divided and may be formed as one connected member. When these are formed as one member, assembling performance of the upper yoke portion is improved. As described above, the angle of the joints  115  can be changed in consideration of workability at the upper yoke portion, and it is also possible to make angles on an inner peripheral side and an outer peripheral side different. For example, when the angle on the inner peripheral side is made so as to increase magnetic resistance, magnetic fluxes concentrated to the inner periphery can be moved to the outer peripheral side to uniform magnetic fluxes at the iron core legs. 
     A plate thickness of an amorphous alloy is extremely thin as compared with a silicon steel sheet and the thickness tends to be uneven. Accordingly, it is possible to adopt a method of increasing flatness of the laminated block by combining a portion with a large plate thickness and a portion a small plate thickness in good manner. It is also possible to obtain necessary flatness by inserting a thin insulating material or the silicon steel sheet between the laminated blocks. 
       FIG. 4  shows a cross-sectional view of the cross section A of  FIG. 3( a ) . In the vicinity of the center of the iron core material  107  and the iron core material  108  in a lamination direction (Y-axis direction), the lamination surface partition  800  having a flat surface parallel to the iron core material is arranged. The plate-shaped material boundary partition  900  is arranged between the laminated block of the iron core material  107  and the laminated block of the iron core material  108 . The lamination surface partition  800  and the material boundary partition  900  are manufactured by metal and so on insulated by an insulating material, varnish or the like. The outer periphery of the iron core material  107  and the iron core material  108  is surrounded by the core fixing metal fitting  500  which is not shown in  FIG. 3( a ) . The core fixing metal fitting  500  is formed of materials with high strength such as iron and epoxy resin. The iron core  100  is formed by laminating the iron core material  107  and the iron core material  108  along the core fixing metal fitting  500  and the material boundary partition  900 . End surfaces of the amorphous alloy tend to be irregular as compared with end surfaces of the slit-processed silicon steel sheet. Therefore, workability of lamination can be improved by arranging the material boundary partition  900  and the core fixing metal fitting  500  functioning as guide members on both sides of the iron core as in the embodiment. As end surfaces of the joints  115  can be also aligned according to the above structure, loss in the joints  115  can be suppressed and iron core characteristics can be improved. Furthermore, the lamination surface partition  800  can function as a reference surface used at the time of laminating the iron core as well as can function as a core in the lamination direction, therefore, the strength of the iron core leg can be increased and the iron core with high resistance to vibration at the time of transportation can be obtained. 
     It is necessary to pay attention so as not to form a circuit in the same direction as the coil by the lamination surface partition  800  when the core fixing metal fitting  500  is a conductor such as iron, however, the attention is not necessary when the core fixing metal fitting  500  is formed of the insulating material. Even when the core fixing metal fitting  500  is formed of the conductor, the lamination surface partition  800  can be arranged at an arbitrary position in the lamination direction (Y direction) which is not shown as long as at least one break is formed. 
     Varnish is applied to contact portions of the core fixing metal fitting  500 , the lamination surface partition  800  and the material boundary partition  900  at the laminating work, thereby fixing these members to some degree in a dry process after the assembly and obtaining the structure having higher strength. 
       FIG. 5  shows a cross-sectional view of a cross section B of  FIG. 3( a ) . The outer periphery of the iron core material  104  and the iron core material  105  is surrounded by the core fixing metal fitting  500  which is not shown in  FIG. 3( a ) . Fastening in the lamination direction is performed by the lower fasteners  400  which is not shown in  FIG. 3( a ) . In the iron core of the amorphous alloy, not only it is difficult to expect improvement of strength by fastening as in the case of the silicon steel sheet but also excessive fastening causes tremendous deterioration of characteristics. Accordingly, it is necessary that the iron core has the structure not depending on the strength for securing safety in the assembling work and for resisting transportation. The core fixing metal fitting  500  and the material boundary partition  900  according to the invention also have a function of preventing excessive fastening by the upper fasteners  300  or the lower fasteners  400 , and sizes are determined so that the fastening from both sides in the lamination direction becomes a proper size. The lower fasteners  400  have fixing portions to the base  700  positioned at a lower part of the inner structure and fixed by bolts. A clearance  1000  between the base  700  and the core fixing metal fitting  500  is filled with an insulating material such as a press board to prevent movement to the lower part. 
       FIG. 6  shows a view obtained by extracting only the fixing structure of the iron core from  FIG. 1 . Core fixing metal fitting and fastener connecting portions  503  for connecting to the upper fasteners  300  and the lower fasteners  400  are provided at upper and lower ends of the core fixing metal fitting  500 , which are fastened to the upper fasteners  300  and the lower fasteners  400  by bolts as shown in  FIG. 1 . The coil  200  is arranged at a position between the upper and lower core fixing metal fitting and fastener connecting portions  503 . 
     Next, a lamination procedure of the iron core will be explained. As the upper yoke portion is lastly formed, other portions which are the upper fasteners  300 , the lower fasteners  400  and the core fixing metal fitting  500  as a framework are first fastened by bolts. To explain the procedure by especially citing the fastening between the lower fasteners and the core fixing metal fitting  500 , the lower fasteners are arranged on both sides with the iron core  100  interposed therebetween. First, one lower fastener of them, for example, a left lower fastener  400  and the core fixing metal fitting  500  are fastened by a bolt. The left lower fastener  400  and the iron core fixing metal fitting  500  in  FIG. 5  are rotated by 90 degrees to fall sideways though they are already in a standing state in  FIG. 5 . Next, iron core materials are laminated from above (from the right side in the standing state in  FIG. 5 ) by using the iron core fixing metal fitting  500  as a guide member. After that, the other lower fastener is attached and both lower fasteners  400  are fastened by using the fastener fastening studs  600  (see  FIG. 1 ). Concerning the core portion, the laminating is performed in the same manner and the iron core is inverted by 90 degrees by an inverting machine to be in a state where the coil  200  can be inserted, and the coil  200  is inserted. 
     In  FIG. 6 , when a member in a region arranged in the yoke portion is denoted by  501  and a member in a region arranged in the core portion is denoted by  502  in the iron core fixing metal fitting  500 , an insulating material such as a press board is interposed between  501  and  502  for adjusting the size, it is also possible to integrally form  501  and  502  by welding the place. Cylindrical stoppers for preventing excessive fastening may be disposed in the fastener fastening studs  600 , and structural strength can be improved by increasing a cross-sectional area of the cylinder and increasing the contact area. 
     Next, the lamination in the upper yoke portion will be explained. In the joints  115  (see  FIG. 3 d   ) where the yoke portion iron core is combined with the core portion iron core, it is required that respective iron cores are arranged accurately with each other. However, respective pieces of the amorphous alloy are extremely thin, therefore, deflection, unfastening of the laminated body and so on may occur in the laminated block of the amorphous alloy, and workability is low on its own. Accordingly, iron plate guide members having a thickness of 1 mm or less are arranged at the outermost periphery in the lamination direction of the yoke portion iron core, and the yoke portion iron core is sandwiched between the iron plate guide members. According to the structure, the yoke portion iron core can be stabilized and workability can be improved. The iron plate guide members may have a length approximately equivalent to that of the yoke portion iron core for stabilizing the entire yoke portion iron core, or may have a shorter length and be arranged only in the vicinity of the joints  115 . 
     As the assembling work, the inner peripheral side iron core is first assembled, then, the material boundary partition  900  is arranged, and lastly, the outer peripheral side iron core is assembled. The iron plate guide members are not removed until insertion of laminated bodies of several blocks is completed, and are collectively removed after the laminate has a certain thickness and the amorphous alloy is stabilized. The work is repeated to thereby insert all blocks. 
     It is also possible to use a PET resin film having a thickness of approximately 0.05 mm instead of the iron guide member. In this case, the film is arranged so as to protrude from the yoke portion iron core by approximately 1 mm in the longitudinal direction of the yoke portion iron core, and respective blocks of the upper yoke may be laminated by using the protrusion of the film as a guide. In the case of the thin film, the guide may be sandwiched in advance at the time of laminating in the core portion. 
     As another method for stabilizing the upper yoke portion at the time of assembling work, there is a method of coating the periphery of joints with resin. A small amount of coating material is applied to end surfaces of the yoke portion iron core which has been cut and laminated for each laminated block. As coating materials, soft resins with least deterioration of characteristics are preferably used, however, hard materials with high deterioration of characteristics may be used according to work environment or the size of the iron core. 
     Embodiment 2 
       FIG. 7  shows a front view of the iron core  100  according to a second embodiment of the invention. In the same manner as  FIG. 3 d    of the first embodiment, pairs of iron core laminated bodies which are iron core materials  107  and  108 ,  101  and  102 , and  104  and  105  are arranged side by side, in which the first laminated block and the second laminated block are laminated. A point different from the first embodiment is that material widths of the iron core materials  107  and  108  differ from each other. Similarly, material widths differ also between  101  and  102  as well as between  104  and  105 . In the core portion of the central iron core leg in three iron core legs, the laminated block of the iron core material  110  with a smaller material width and the laminated block of the iron core material  111  with a larger material width are arranged in parallel, and these are laminated alternately in right and left sides for each laminated block in the same manner as the first embodiment. In the case of the second embodiment, the iron core materials  111  with the larger material width overlap in laminated blocks adjacent in the lamination direction by a prescribed width. A region between a boundary between the iron core materials  110  and  111  in the first laminated block and a boundary between the iron core material  110  and  111  in the second laminated block corresponds to an overlapping margin  117  of the iron core material  111 . It is difficult to arrange the material boundary partition  900  in the central iron core leg due to the existence of the overlapping margin  117 , however, the strength of the iron core leg is secured even when the material boundary partition  900  is omitted as the overlapping margin  117  functions as a shaft. The overlapping margin  117  corresponds to the difference of material widths between materials  107  and  108 ,  101  and  102 ,  104  and  105 , and  110  and  111 . The difference can be arbitrarily selected so as to correspond to the shape of the iron core for the purpose of omitting the material boundary partition  900 . 
     In the explanation of the embodiment, the example in which the iron core materials  110  and  111  used for the first laminated block is used for the second laminated block by turning over the materials  110  and  111  as they are. However, also in the embodiment in which laminated blocks are formed by combining materials having different iron core widths, the boundaries of iron core materials can be aligned in the first laminated block and the second laminated block by making the shape of the iron core material forming the second laminated body different from the shape of the iron core materials  110  and  111  forming the first laminated block. In this case, the material boundary partition  900  can be inserted into the boundary. 
     In the yoke portion, the iron core material with the larger material width is used for the inner side iron core materials  101  and  104 , and the iron core material with the smaller material width is used for the outer side iron core materials  102  and  105 , thereby integrating the iron core materials  101  and  104  completely separated in the first embodiment into one member respectively. 
     The embodiment considers that characteristics of the amorphous alloy will be deteriorated as the material width is increased. That is, the iron core with the larger material width and worse characteristics is arranged on the inner peripheral side, thereby dispersing magnetic fluxes concentrated to the inner peripheral side toward the outer peripheral side and obtaining effect of improvement in characteristics by uniforming magnetic fluxes in the iron core legs. 
     It is also possible to provide a hook shape by a cutter having a notch of the hook shape at material cut portions on both sides to be joined to thereby perform guidance and prevent deviation at the time of lamination. 
     Embodiment 3 
       FIG. 8  shows a front view of the iron core  100  according to a third embodiment of the invention. In the same manner as  FIG. 3 d    of the first embodiment and  FIG. 7  of the second embodiment, pairs of iron core laminated bodies which are iron core materials  107  and  108 ,  101  and  102 , and  104  and  105  are arranged side by side, in which the first laminated block and the second laminated block are laminated. In the embodiment, the iron core materials  110  and  111  forming the central iron core leg have the same width, however, the iron core materials  107  and  108  forming the outer side iron core leg and the iron core materials  101  and  102  in the yoke portion have different iron core widths from each other, respectively. As the central iron core leg is formed by combining two iron cores which have the wider width in iron cores having two kinds of widths forming the outer side iron core legs, the iron core cross-sectional area is larger in the central iron core leg than in the outer side iron core legs. Since the central iron core leg is arranged so as to be sandwiched between both-side iron core legs and the coil  200 , heat tends to be accumulated and is difficult to be cooled as compared with both-side iron core legs. When the iron core is not sufficiently cooled and the temperature of the iron core is increased, characteristics of the iron core deteriorate. In the embodiment, the cross-sectional area of the central iron core leg in which deterioration in characteristics tends to occur due to the temperature increase is widened as compared with the iron core legs on both sides, thereby reducing the load applied to the central iron core leg and suppressing deterioration in characteristics at the central iron core leg. Two iron core materials with the wider material width are combined and used for the central iron core leg, thereby increasing the cross-sectional area of the iron core to be larger than that of the outer side iron core legs. Conversely, it is possible to reduce the cross sectional area of the iron cores to be smaller than that of the central iron core leg by combining two iron core materials with the smaller material witch for the outer side iron core legs. When the central iron core leg is formed by aligning the iron core materials having the same material width, the material boundary partition  900  is preferably arranged in the same manner as Embodiment 1. 
     Embodiment 4 
       FIG. 9  shows a front view of the iron core  100  according to a fourth embodiment of the invention. In the present embodiment, three iron core materials are arranged side by side, and the first laminated block and the second laminated block are laminated, which differs from the first to third embodiments. The central iron core leg is formed by iron core materials  110  to  112 . When the material having the same shape is used for the iron core materials  110  and  112 , kinds of materials can be suppressed and manufacturing costs can be reduced. The example in which three iron cores having the same material width are aligned is shown in  FIG. 9 , however, the iron core material having a different width may be used for part of the iron core. The iron core  100  formed by aligning four or more iron core materials is also an example of the embodiment of the invention. The iron core formed by using a material having a different material width for at least one part of the iron core is also an example of the invention. 
     Embodiment 5 
       FIG. 10  shows a cross-sectional view of an iron core leg of the iron core  100  according to a fifth embodiment of the invention. 
     When the coil  200  has a cylindrical shape, a large clearance is generated between the coil  200  and the core fixing metal fitting  500  in the shape of the iron core  100  shown in  FIG. 4 , and a ratio of the area (space factor) of the iron core occupied inside the coil is reduced. Accordingly, a width of the iron core material positioned in the vicinity of the center in the lamination direction (Y-axis direction) with respect to the iron core  100  is formed to be wider than widths of the iron core material arranged on outer sides in the lamination direction (Y-axis direction). According to the structure, the cross-sectional shape of the iron core  100  becomes a shape close to the cylindrical shape of the coil, therefore, the clearance between the coil  200  and the core fixing metal fitting  500  is reduced and the space factor can be increased. An example in which iron core widths of three kinds of more are formed as shown in  FIG. 11  is also part of the embodiment. When the iron cores with a larger kinds of widths are combined to form the cross-sectional shape of the iron core to be an approximately circular shape, the space factor can be further increased. In the embodiment in which iron cores with many kinds of widths are combined as described above, the structure of the iron core becomes complicated and assembling performance is reduced, however, the reduction of assembling performance can be suppressed by using the core fixing metal fitting  500  as a guide for the laminating work of the iron core as in the invention. A reinforcing effect can be also obtained after the laminating. 
     Embodiment 6 
       FIG. 11  shows a cross-sectional view of an iron core leg of the iron core  100  according to a sixth embodiment of the invention. An outer shape of the iron core is an approximately cylindrical shape of the coil  200  by making iron core widths different according to positions in the lamination direction (Y-axis direction). Another feature of the present embodiment is a point that the outermost periphery in the lamination direction is formed by the single laminated block and plural laminated blocks are not aligned in the X-axis direction. Accordingly, the material boundary partition  900  does not reach the outermost periphery in the lamination direction (Y-axis direction). As mentioned in the explanation of  FIG. 10 , the core fixing metal fitting  500  has a multistage shape extending along the outer shape of the iron core. 
     In the present embodiment, the material widths are clearly different in the laminated block in the outermost periphery of the lamination direction (Y-axis direction) and in an adjacent inner side laminated block, and the fastening load applied from the side of the laminated block in the outermost periphery is received only by part of regions in the inner side laminated block. In order to reduce the deviation of the load, for example, an iron plate, a silicon steel sheet, a thick press board and the like which are wider than the area of the inner side laminated block may be inserted between the outermost laminated block and the adjacent inner side laminated block. 
     The dimension of a circumscribed circle of the core fixing metal fitting  500  is formed to be slightly larger than an inner periphery of the coil  200 , and the coil is inserted while being deformed by contact, thereby maintaining a good contact state after the insertion. The dimensional adjustment is performed also by drying of a coil inner bobbin and the dimension after lubrication, and may be in a range of within 1 mm. The bobbin in this case is preferably a metal such as iron from an aspect of strength. The bobbin arranged in an inner periphery of the coil can be functioned as an insertion guide used when inserting the core fixing metal fitting  500  into the coil by performing processing of a groove having the same shape as a corner of the core fixing metal fitting  500  at a position corresponding to the corner after the iron core is inserted. The bobbin can also have a function of fixing the iron core after the iron core is inserted. The bobbin in this case is preferably a press board having, for example, a thickness of approximately 3 mm. 
     Embodiment 7 
       FIG. 12  shows a cross-sectional view of an iron core leg of the iron core  100  according to a seventh embodiment of the invention. In the present embodiment, a cylindrical periphery fixing material  1100  is arranged around the core fixing metal fitting  500  of  FIG. 11 . The periphery fixing material  1100  connects two members having a semicircular shape on an extension line of the material boundary partition  900  to form an approximately circular shape. As a material, a press board or an iron plate is preferable in an oil-filled transformer, and plastic, a resin or an insulating paper is preferable in a molded transformer. As it is easy to open and close by human power when using a thin insulating material and the like, one member having an approximately cylindrical shape with an opening which can be opened and closed may be used instead of using two semicircular members by being combined. Even in a hard and thick material such as an iron plate or a press board which is difficult to be opened and closed by human power, one member having the approximately cylindrical shape can be used as long as it has the opening with a size allowing the iron core material to be inserted. The periphery fixing material  1100  is fixed by being sandwiched between the outermost periphery of the iron core  100  in the lamination direction (Y-axis direction) and the upper fastener  300  or the lower fastener  400  in the yoke portion, and is fixed by an insulating tape and so on over an circumferential direction at positions where the fastener is not arranged such as the core portion. When the embodiment is applied to the molded transformer in which the appearance is particularly important, the joint surface and the inner structure can be hidden. It is also possible to suppress accumulation of dust and dirt on the surface of the iron core  100  or on the outer peripheral surface of the core fixing metal fitting  500 . Furthermore, a soundproof effect can be also obtained. 
     Even in the case of adopting the method of forming the outer shape of the iron core  100  into an approximately circular shape as in the fifth embodiment and the sixth embodiment, it is extremely difficult to form a perfect circle because so many kinds of iron core widths are necessary to realize the shape. According to the present embodiment, the outer periphery of the periphery fixing material  1100  has a shape extending along the inner periphery of the coil  200 , therefore, the iron core  100  and the coil  200  can be firmly fixed even when the outer periphery of the iron core  100  is not formed into the perfect circle. In the oil-filled transformer, varnish is applied to the inner periphery of the coil  200  and bonding is performed in a dry process to thereby suppress displacement of members. 
     In the case of the large-capacity transformer, it is necessary to largely secure an insulation distance between the iron core  100  and the coil  200 . A cooling duct is arranged in a clearance between the iron core  100  and the coil  200 , thereby improving cooling performance while securing the insulation distance. 
     Embodiment 8 
       FIG. 13  shows an iron core cross-sectional view in the yoke portion of the iron core  100  according to an eighth embodiment of the invention. An iron core fixing member  1200  formed of an insulator is arranged instead of the core fixing metal fitting  500  according to the first to seventh embodiments, and the periphery fixing material  1100  having an arc shape which is welded to the upper fastener  300  and the lower fastener  400  is arranged at the outside thereof, thereby fixing the iron core  100 . The periphery fixing material  1100  is made of iron as it is welded. The lamination surface partition  800  according to the present embodiment is formed of an insulating material, which is fixed by being sandwiched by boundary portions  1300  of the periphery fixing material  1100 , therefore, the periphery fixing material  1100  has a structure in which a circuit is not formed. In the case where the lamination surface partition  800  is formed of materials other than the insulator, the circuit is not formed by performing varnish processing near a contact portion between the periphery fixing material  1100  and the lamination surface partition  800 , or a by a method of newly interposing the insulating material. The periphery fixing material  1100  may be partially arranged in accordance with the size of the iron core  100 . 
     As the cross-sectional shape of the iron core becomes close to the circular shape, the area of a flat surface portion contacting the upper fastener  300  or the lower fastener  400  is reduced. In the present embodiment, the periphery fixing material  1100  is fixed to the upper fastener  300  and the lower fastener  400  by welding, therefore, the iron core can be firmly fastened and fixed even when the flat surface portion is narrow. 
     Embodiment 9 
       FIG. 14  shows an iron core cross-sectional view of the iron core  100  according to a ninth embodiment of the invention. In the present embodiment, the lamination surface partitions  800  are arranged at plural positions in the lamination method, and holes or grooves are formed at positions corresponding to the lamination surface partitions  800  in the periphery fixing material  1100  formed in a circular shape so that the lamination surface partitions  800  are fitted thereinto. The lamination surface partitions  800  and the periphery fixing material  1100  are fitted and fixed to each other, thereby fixing the iron core material. In a periphery fixing metal fitting  1400  arranged in an outer periphery of the periphery fixing material  1100 , holes are formed only at positions corresponding to the lamination surface partitions  800  arranged in the vicinity of the center of the lamination direction (Y-axis direction), and the lamination surface partitions  800  are inserted into the holes. 
     Whether the inserted lamination surface partitions  800  are sandwiched and fixed by the periphery fixing metal fitting  1400  or not depends on the strength of the lamination surface partitions  800 , which can be arbitrarily selected. 
     In the respective embodiments of the invention, the laminated iron core formed of the amorphous alloy is cited as the example, however, the invention is not always limited to this, and the invention can be also applied to a laminated iron core formed of the silicon steel sheet. The invention can also be applied to a combination of the amorphous alloy and the silicon steel sheet. In the case of the iron core formed of the amorphous alloy, the reinforcing effect and productivity improvement effect of the iron core are higher than the case of the laminated iron core formed of the silicon steel sheet. 
     The silicon steel sheet may be used for the lamination surface partition  800 , thereby improving the strength. It is also preferable that silicon steel sheets having the same material width are arranged on the front and back of the lamination surface in the laminated block of the amorphous alloy and the amorphous alloy is interposed, thereby further increasing the strength of the iron core legs and improving workability of inserting the upper yoke portion. In the case where the materials are combined as described above, characteristics are better by reducing a ratio of the silicon steel sheet. For example, when a structure in which the silicon steel sheets are arranged on both sides of 20 pieces of amorphous alloys is adopted, the silicon steel sheets occupy approximately the half of the entire iron core, therefore, an iron loss is increased as compared with the case where the amorphous alloy is 100% used. On the other hand, for example, when the ratio of the silicon steel sheet is suppressed to within 10% of the whole lamination thickness, the iron loss can be suppressed to approximately +30% with respect to characteristics of the amorphous alloy of 100%. Though the ratio of the silicon steel sheet depends on a required strength of the iron core, the silicon steel sheets are disposed, for example, in units of 10 blocks of laminated blocks of the amorphous alloy. The silicon steel sheets maybe limited only to the upper yoke portion by considering workability, and the silicon steel sheets may be applied to other leg portions. 
     As the fixing method of the iron core  100 , a method in which round holes are made on the upper fastener  300 , the lower fastener  400  and the core fixing metal fitting  500 , each core portion and the yoke portion, and insulated round bars are inserted thereinto may be adopted. According to the method, the iron core can be fixed more firmly, for example, while omitting the filling of the clearance  1000  in  FIG. 5 . 
     REFERENCE SIGNS LIST 
     
         
           100  iron core 
           115  joint 
           117  overlapping margin 
           200  coil 
           300  upper fastener 
           400  lower fastener 
           500  core fixing metal fitting 
           501  core fixing metal fitting/yoke portion 
           502  core fixing metal fitting/core portion 
           503  core fixing metal fitting/fastener connecting portion 
           600  fastener fastening stud 
           700  base 
           800  lamination surface partition 
           900  material boundary partition 
           1000  clearance 
           1100  periphery fixing material 
           1200  iron core fixing material 
           1300  boundary portion 
           1400  periphery fixing metal fitting