Patent Publication Number: US-3875660-A

Title: Method of producing laminated magnetic cores for inductive electric apparatus

Description:
United States Patent 11 Kobayashi et al.  
 1 1 METHOD OF PRODUCING LAMINATED MAGNETIC CORES FOR INDUCTIVE ELECTRIC APPARATUS [75] Inventors: Kazuhiro Kobayashi: l-liroshi Saito.  
 both of Hitachi; Yukio Ogawa. Katsuta&#39;. Koki Yoshida; Isamu Kondo, both of Hitachi. all of Japan [73] Assignee: Hitachi, Ltd., Tokyo. Japan {22] Filed: Apr. 13, 1973 [21] Appl. No.: 350,970  
 [52] 1.1.5. Cl. 29/609; 29/203 L; 214/6 DK {51] Int. Cl. H0&#34; 7/06 [581 Field of Search 29/609, 203 R 203 L; 214/6 DK; 336/234, 212, 217  
 [56] References Cited UNITED STATES PATENTS 3.423.814 1/1969 Davis 29/203 L 3.511523 5/1970 Mittermaier et al. 29/203 L 3.540.120 l 1/1970 DeLaurentis ct a1. 29/609 FOREIGN PATENTS OR APPLICATIONS 228,772 3/1966 U.S.S.R. 29/203 L 1 Apr. 8, 1975 Pfillldl) E.\&#39;aminerCarl E. Hall Attornev, Agent. or FirmCraig &amp; Antonclli 1 71 ABSTRACT The cut silicon steel plates are laid one upon the other conversely to the order of lamination of the core. Such stacked silicon steel plates are sucked up and transferred one by one successively from the topmost one of said stack of plates, and the transferred silicon steel plates are parted or separated in the right and left directions transverse to the direction of transfer in a predetermined order. the thus separated respective silicon steel plates being further transferred successively in a given order so that they are congruous to the respective core leg positions on a core carrier means so as to effect automatic lamination of core leg portions, with lamination of the yokes magnetically connecting the adjoining core leg portions being performed by manual operations, thereby realizing reduction of working time and cost required for completing lamination of large-sized laminated magnetic cores.  
 2 Claims. 20 Drawing Figures sum 1 BF 8 PI&#39;JENTEBAFR 81975 F I G.  
 PRIOR ART a A c F l G.  
 PRIOR ART F l G.  
 PRIOR ART PRIOR ART PATENTEB APR 81975 FIG. 5  
  METHOD OF PRODUCING LAMINATED MAGNETIC CORES FOR INDUCTIVE ELECTRIC APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved method of an apparatus for producing laminated magnetic cores for use in inductive electric apparatus such as power transformers, reactors, etc.  
 2. Description of the Prior Art In general, the magnetic cores of the type used in large-sized inductive electric apparatus such as transformers or reactors used for electric power line are formed in a laminar structure having core leg portions and yoke portions by laying the suitably cut silicon steel plates one on the other in regular succession. Usually, the silicon steel plates forming the leg portions and those forming the yoke portions are placed one on the other with the respective adjoining edges staggered relative to each other alternately for each or every several pieces of plates, and such layered portions are fastened securely by clamping works conducted after completion of the lamination so as to maintain the magnetic and mechanical coupling in a preferred form. Nor mally, joining of the silicon steel plates forming the core leg portions and those forming the yoke portions is made such that their respective edges will make the right angles or an inclination of 45 relative to each other. The manner and configuration of such joining of silicon steel plates for forming laminated magnetic cores are shown in detail in for example U.S. Pat. No. 2,300,964, so that no detailed explanation on such matter is given here.  
  Heretofore, for practicing such lamination of silicon steel plates, there has been used a method in which a means for clamping or fastening one side of each core is disposed horizontally on a support block and then the silicon steel plates, which have been cut into a given size from a hoop of silicon steel strip, are placed in layers on said fastening means one by one in succession. in this case. the laminating works must be made such that the edges of the silicon steel plates forming the leg portions will attach to the corresponding edges of the silicon steel plates forming the yoke portions at the same laminating position, but in the next laminating position said attached edges will be shifted or staggered relative to each other. Therefore, such laminating works require much time and labor.  
  Further, when producing the cores for power transformers, such lamination must be practiced such that at least each leg portion will have a sectional shape close to a circle so as to conform to the configuration of the winding.  
  Therefore, in accomplishing such lamination, it is necessary to laminate the silicon steel plates which are narrow in width at one side of the core leg portion and which are gradually increased in width toward the center of said leg portion and then again narrowed down gradually toward the other side of said portion. Thus, there is necessity of preparing the silicon steel plates of various sizes for composing the core leg and yoke portions. Laminating such various sizes of silicon steel plates one by one with manual operations invites further increase of working time.  
 SUMMARY OF THE INVENTION The present invention has for its object to provide a method of producing laminated magnetic cores for in ductive electric apparatus, which method permits automation of the substantial part of the laminating works in the manufacture of laminated magnetic cores.  
  It is also envisaged in the present invention to provide an improved apparatus for practicing the above-said method.  
  More specifically, the present invention is intended to provide a method and an apparatus of the type just described, whereby the laminating works for forming the leg portions of laminated magnetic cores are substantially automated, with only the laminating works for forming the yoke portions being practiced by manual operations, thereby realizing substantial reduction of time and labor required for the laminating works.  
  According to the present invention, a plurality of silicon steel plates, which have been cut into a suitable configuration, are first parted or grouped into those for forming the leg portions and those for forming the yoke portions, and these grouped silicon steel plates are respectively stacked up on a bogie conversely to the order of lamination of the core.  
  The silicon steel plates for forming the leg portions are sucked up or attracted by a suitable sucking or attracting means such as a sucking pad operated at reduced pressure or an electromagnet and delivered out one by one from the topmost piece of the stack onto a first conveyor. Each of the silicon steel plates thus transferred onto the first belt conveyor is suitably orientated in the direction of the cut edges at both of its ends when it passes through a reversing device which is turned reversely along the direction of transfer of the plates upon receiving a reversing instruction, and the thus suitably orientated plates are transferred onto a second belt conveyor and then further to a third conveyor, during which period the respective silicon steel plates are separated in a predetermined order so as to conform to the intervals between the core leg portions. the thus separated plates being carried successively onto a core carrier board whereon joining of the silicon steel plates for the yoke portions is performed by manual operations.  
  Thus, according to the present invention, the entire core constructing works can be carried out with attendance of only one worker stationed near the core carrier board.  
  In the present invention, joining of the core leg and yoke portions is practiced such that all of the joined parts will be at right angles to each other, and also during formation of the core, both edges of each silicon steel plate present a symmetical configuration relative to the widthwise direction, so that during these operations there is no need of operating said reversing device and, in some cases, such reversing device may be omitted.  
  Also, above-said separating means may be suitably adjusted to provide a desired separating pattern according to the number of core legs and, further, the operating distance thereof can be reset in accordance with the distance between the respective core legs.  
  Now, the present invention is described in the concrete by way of a preferred embodiment thereof.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a rough sketch showing a three-legged core where the leg portions are joined at right angles relative to each other;  
  FIG. 2 is a rough sketch showing a three-legged core where the leg portions are joined at the angle of 45 relative to each other;  
  FIG. 3 is a rough sketch showing a five-legged core where the leg portions are joined at the angle of 45 relative to each other;  
  FIG. 4 is a sectional view of a core leg portion as taken along the line IV IV of FIG. 2;  
  FIG. 5 is a flow sheet illustrating the steps of manufacturing a laminated magnetic core according to the present invention;  
  FIGS. 6A and 6B are perspectively views showing the conditions of the core leg portion constructing silicon steel plates placed in layers on a bogie;  
  FIG. 7 is a side elevational view as taken along the line VII VII of FIG. 5, showing a sucking (or attracting) and transferring means and a reversing means embodying the present invention;  
  FIG. 8 is a side elevational view as taken along the line VIII VIII of FIG. 5, showing a parting or separating mechanism embodying the present invention;  
  FIG. 9 is a side elevational view taken along the line IX IX of FIG. 5, showing a core stacking mechanism embodying the present invention;  
  FIG. 10 is a side elevational view showing in detail the construction of the core stacking mechanism;  
  FIG. II is a front view taken along the line XI XI of FIG. 10;  
  FIGS. 12A to 12D are the sketches illustrating the operating behaviors of a stopper which regulates the laminating position of the silicon steel plates constituting the leg portions of each core;  
  FIG. 13 is an illustration showing an example oflaminating pattern of the leg&#39;forming silicon steel plates for constituting a three-legged core; and  
  FIG. 14 is an illustration showing another example of laminating pattern of said plates for forming a threelegged core.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, there is shown schematically a three-legged core construction comprising three legs A B, and C and upper and lower yokes D,, E and F G adapted to magnetically couple said adjoining legs. The silicon steel plates a to g constituting said leg and yoke portions are formed into a rectangular structure where the edge of each said plate meets at right angles with those of the adjoining plates. Said leg and yoke portions are also joined at right-angles to each other.  
  Shown in FIG. 2 is also a three-legged core construction. but in this construction, the silicon steel plates a to g; forming in layers the leg portions A to C and yoke portions D to G are cut at an angle of 45 at their edges to form a trapezoidal structure. and also the leg and yoke portions are joined aslant relative to each other.  
  In case of using oriented silicon steel plates, slant joining allows reduction of the loss of iron material at the junctures, so that usually such slant joining system is employed.  
  In manufacturing large-capacity three-phase transformers, a five-legged core consititution such as shown in FIG. 3 is often employed for lessening the vertical size. In such five-legged core structure, side legs H and I designed to serve concurrently as side yokes are provided on both sides of an arrangement of core legs A 8;, and C around each ofwhich a winding is coiled, and these legs are magnetically coupled by yokes D to G and J K L and M respectively. Also. in the con struction of FIG. 3, the respective silicon steel plates 0 to m forming said leg and yoke portions are cut at an angle of 45 at their edges. It is to be noted that these laminated silicon steel plates are varied in width from one another such that at least those of the core legs on which winding is fitted will have a substantially circular sectional shape as shown in FIG. 4. That is. the width of the respective silicon steel plates is gradually in creased from the ones an and a at both ends. which are narrowest, toward the centrally-positioned one 0 which is broadest, with the intermediate plates 22 22; 23 23&#39;; 24 G24; 6125 25&#39;; and 26 26&#39; being gradually widened in width in that order. so as to form a contour close to a circle as shown in FIG. 4.  
  In order to effect lamination of the respective silicon steel plates in order. these plates are stocked in the reverse order. that is. such that the plate a side will be positioned upwardly and the plate 0 side downwardly. and also the plate a side will be positioned upwardly and the plate n21 downwardly. In stocking such silicon steel plates in piles ready for lamination. it is preferred to have such stacked plates divided into several rows.  
  Referring now to FIG. 5, there is shown a flow sheet showing in successive order the steps for producing a laminated magnetic core according to the present invention. In this figure, numeral I00 designates a bogie or carrier means on which the leg-forming silicon steel plates are stacked, 200 a sucking (or drawing or attracting) and transferring means disposed adjacent said carrier means, 300 a first conveyor means located adjacent said sucking and transferring means. 400 a reversing means disposed adjacent said first conveyor means, 500 a second conveyor means located adjacent said reversing means, 600 a third conveyor means provided adjacent said second conveyor means. said third conveyor means 600 having provided therein a parting or separating means 700 for separating the silicon steel plates into several groups, 800 a core stacking mechanism provided adjacent said third conveyor means, and 900 a bogie or carrier means carrying thereon the yoke-forming silicon steel plates. said carrier means 900 being disposed adjacent said core stacking mechanism 800. Said carrier means comprises a bogie 120 supported on guide rails so that it is able to move in one direction. The silicon steel plates placed in pile on said bogie are arranged either in three rows as shown in FIG. 6A or in two rows as shown in FIG. 6B.  
  In FIG. 6A, the silicon steel plates. which have all been cut into rectangular forms, are arranged in three rows of stacks 130, 140 and 150. The stack consists of the silicon steel plates 131 136 which are placed one on the other such that one with a greater width will come under one with a smaller width. so as to form a lamination at the lower part of a core leg portion when a laminated core is constituted. The stack 140 comprises a block or blocks of silicon steel plates 141 of the same size placed one on the other so as to constitute the central part of the core leg portion. while stack 150 comprises the silicon steel blocks 151 156 placed one on the other such that one with a smaller width will come under one with a greater width so as to form a lamination at the upper side of the core leg portion.  
  In FIG. 6B. the silicon steel blocks, each being cut at 45 at its both ends to form a trapezoidal block. are arranged in two rows of stacks 160 and 170, the stack 160 comprises the silicon steel blocks 161 164 stacked up such that one with a greater width will come beneath one with a smaller width so as to form a lamination at the lower part of the core leg portion when constituting a laminated core. while the stack 170 comprises the silicon steel blocks 171 174 placed in layers such that one with a smaller width will be positioned below one with a greater width so as to form a lamination at the upper part of the core leg portion.  
  In case of forming a large-sized magnetic core. the number of silicon steel blocks used is increased and hence said rows of stacks must be increased accordingly. Also. when it is found difficult to carry all of the blocks on one bogie. two or more such bogies may be used. with the respective stacks of silicon steel blocks being loaded on each of said bogies in the order of lamination practiced.  
  The silicon steel blocks stacked in rows as described above on the bogie 120 are then transferred onto a first conveyor means 300 one by one by a sucking and transferring means 200. In FIG. 7 are shown schematically the mechanical arrangements of such sucking and transferring means 200 and conveyor means 300.  
  The sucking and transferring means 200 consists of an arm 210 secured at one end to a fixed supporting member 211 through a shaft 212. a cylinder 220 mounted below said arm 210 and adapted to charge or discharge fluid (such as oil) pressure, a piston rod 221 provided in said cylinder 220, a suction pad 230 secured to the bottom end of said piston rod 221, and a rocker cylinder 240 operable to rock or swing said cylinder 220 about the shaft 212. Said rocker cylinder 240 is secured at its top end to a fixed supporting member 250 through a shaft 241 and has fitted therein a piston rod 242 which is joined at its end to one end of said cylinder 220 by means of a pin 243.  
  Said both cylinders 220 and 240 are connected to an operating pressure source such as for example a hydraulic pressure source. not shown. through pipes 224, 225. and 244. 245, respectively. in the directions of arrows 1. 2. and 3. 4. respectively.  
  Thus. when hydraulic pressure is applied into said cylinder 220 in the direction of arrow 2. the piston rod 221 is urged to move upwardly in the direction of arrow 5 along with the suction pad 230 at its bottom end. whereby the topmost one of a stack of silicon steel blocks on the bogie 120 (said topmost block being sucked to said suction pad) is raised up. Then. when hydraulic pressure is applied into the rocker cylinder 240 in the direction of arrow 4, the piston rod 242 is urged to move in the direction of arrow 6. causing the cylinder 220 to swing to the position indicated by chain lines in the figure (FIG. 7). As said cylinder 220 reaches this position. air is introduced into the suction pad 230 to release the silicon steel plate 50 so that said block will drop onto the first conveyor means 300.  
  This first conveyor means 300 comprises a belt conveyor 320 supported by beams 310. said belt conveyor 320 being constituted from an endless belt 327 passed round pulleys 324, 325 and 326 supported by shafts 321. 322 and 323. respectively. On the surface of said endless belt 327 are provided protuberances 328 at given intervals.  
  Any selected one of said pulleys. such as pulley 326. is provided with a sprocket 331 which is connected through a chain 332. a sprocket 333, another chain 334 and another sprocket 335 to a power source 330.  
  Thus. when the power source 330 is operated, said sprockets and chains are driven to move in the directions shown by respective arrows, causing the belt 327 to move accordingly in the direction of arrow 7.  
  Numeral 340 denotes a channel-shaped guide provided along and toward the upper part of the belt conveyor 320, said guide having a chute or guide portion 341 adapted to guide the silicon steel block 50 from the topmost part of the belt conveyor 320 down to the reversing means 400 on the next stage. The reversing means 400 disposed adjacent said first conveyor means 300 is provided on a beam 310 in a slant state in conformity to the inclination of the guide portion 341 of said channel-shaped guide 340. This reversing means 400 consists of a body portion 410 formed from a pair of plate members 411 and 412 disposed parallel to each other so as to receive thereinto the silicon steel plate 50, stoppers 421 and 422 provided at both ends of said body portion, and a rack means 430 operable to turn said body portion about 180 in the direction of arrow Said stoppers 421 and 422 are designed to be operated by suitable means. such as for example hydraulic cylinders 423 and 424. according to a reversion instruction described later. so as to close the inlet and outlet ofthe silicon steel plate 50 contained in the body portion 410. The rack means 430 consists of a rack 432 engaged with a pinion 431 mounted substantially in the center of said body portion 410 and a hydraulic cylinder 433 operable to move said rack 432 in the direction of arrow 9.  
  Numerals 434 and 435 denote pipes for supplying and discharging pressurized oil into and from said hydraulic cylinder 433.  
  The silicon steel plate 50 released from the reversing means 400 is then further transferred onto the second conveyor means 500 through a guide means 440. This second conveyor means 500 is so designed as to change the direction of transfer of the silicon steel plate 50 by as shown in FIG. 5. Said means is constructed as a roller conveyor comprising rollers 520 disposed in juxtaposed relation on a beam 510. Said rollers 520 are supported on said beam 510 by respective shafts 521 provided with sprockets 523 which are connected to each other by a chain 524 and further to a driving power source 530 by another chain as shown in FIG. 9.  
  Numeral 540 denotes guide rollers provided in opposition to said respective rollers 520. Said guide rollers are depressed downwardly by the respective hydraulically operated cylinders 550 to press the silicon steel plate 50 against the conveyor to ensure secure transfer of the block.  
  The silicon steel plate 50, which has been changed in its direction of transfer by the second conveyor means 500. is then transferred onto the third conveyor means 600. This third conveyor means 600 is also of a roller conveyor system comprising a plurality of rollers 621 mounted at fixed intervals on a shaft 620 which is journalled at its both ends by a beam 610 as shown in a front view of FIG 8. These roller conveyors are provided in several sets along the direction of transfer of the silicon steel plate as shown in FIG. 9, and the sprockets 622 provided on the respective shafts 620 of said conveyors are connected to each other by a chain 623 and further to a driving power source 630 so that they are operated synchronously to each other. It will be also seen that said second and third conveyor means 500 and 600 are connected by a chain 640, as shown in FIG. 9, to allow synchronous operation of said both conveyor means.  
  This third conveyor means 600 is provided with a separating means 700 for parting or separating the silicon steel plate which have been transferred thereto. The details of such separating means are shown in FIG. 8. Shown in the figure is an embodiment adaptable for forming a three-legged corev Numerals 711, 713 and 715 indicate press rollers adapted to allow transfer of the silicon steel plate by holding them at the respective separated positions. These rollers are depressed or raised up by the operation of the respective hydraulic cylinders 712, 714 and 716. Each of said rollers is also supported by a shaft 717 to maintain a predetermined position Particularly. the press rollers 71] and 715 disposed on both sides are secured at their respective positions by feed screws 718 and 719, respectively, provided on the shaft 717. These feed screws 718 and 719 are formed with threads arranged at a same pitch but in the opposite directions relative to each other. According to this arrangement, when the shaft 717 is rotated. the press rollers 711 and 715 on both sides can be moved simultaneously through a same distance either outwardly or inwardly while maintaining the central press roller 713 at its fixed position.  
  For operation of the shaft 717, a gear 720 is provided at one end of said shaft 717, said gear 720 being meshed with a gear 722 secured to an end ofa handle 721 provided on the beam 610.  
  Owing to the above-described mechanism, the silicon steel plate can be properly transferred while maintained at their respective parted or separated positions.  
  Numeral 730 indicates a parting pin for effecting parting of the silicon steel plate. This pin 730 is moved in the direction of arrow 10 or 10 by means ofa chain 733 passed round the sprockets 731 and 732 provided on both legs of the beam 610. By this movement of the pin 730, the silicon steel plate carried to the center of the conveyor belt from the second conveyor means 500 are parted in the right and left directions. Numerals 50A, 50B and 50C indicate the silicon steel plate which were parted or separated in the above-said manner. Such separating operation can be practiced by rotating the sprocket 731 after selecting its proper direction of rotation.  
  Indicated by numeral 740 is a hydraulically operated cylinder provided with a piston rod 741. At the end of said piston rod 741 is provided a rack 743 which is movable guided by rollers 742. Engaged with said rack 743 is a pinion 744 which is connected through a gear 745, a sprocket 746 and a chain 747 to said sprocket 731. Thus, it will be understood that the direction and distance of movement of said pin 730 can be determined by selecting the direction and distance of movement of said rack 743.  
  Such separating operation is performed according to the selected separating pattern provided by a separator means which is described later.  
  Numerals 751 and 752 designate the silicon steel plate positioning stoppers provided on both sides of the array of rollers 62]. These stoppers are engaged with the screws 753 and 754, respectively, which are threaded at a same pitch but in the opposition directions relative to each other. Both of said screws 753 and 754 are mounted on a shaft 755 supported by the legs of the beam 610, one end of said shaft 755 being engaged with a bevel gear 757 through another bevel gear 756. Said bevel gear 757 is rotated by an instruction from a silicon steel plate width detector (not shown) to determine the positions of the stoppers 751 and 752.  
  After the respective silicon steel plate 50A 50C have been duly separated by the abovedescribed separating operations, the hydraulic cylinders 713, 714 and 716 are operated to depress the press rollers 711, 713 and 715 against said respective plate to deliver them to the next core carrier means 800 with rotation of the rollers 621.  
  The detailed mechanism of such core stacking mechanism 800 is shown in FIGS. 9 to above-described The core carriage 801 is supported through wheels 804 on rails 803 laid on a support 802 which is moved up and down by a lifting means 806 provided in a pit 805. In the shown embodiment. said lifting means 806 is composed from several pieces of threaded bars 808 arranged to be operated by an electric motor 808 through reduction gearing.  
  Provided on said carrier 801 are a support plate 809 disposed at a position corresponding to the core leg portion and channel-shaped core fastening elements 810 disposed at a position corresponding to the yoke portion. The silicon steel plate are laid up in layers on said support plate 809 and fastening elements 810 so as to constitute a laminated core 811.  
  Numeral 812 designates patch plates, made of wood or other suitable material, disposed between said support 809 and carriage 801.  
  Provided above said core carriage 801 are silicon steel plate holder means 820 suspended down from a beam 813 so as to be movable through a suitable distance. These holder means 820 are arranged in parallel to each other and provided in a number corresponding to the number of core legs. Thus, in case of forming a three-legged core, said holder means are provided in three parallel sets. Each of said silicon steel plate holder means 820 consists of a pair of parallel frameworks 821. feed rollers 822 provided in each of said frameworks, electric motors 825 each being adapted to rotate each said feed roller 822 through bevel gears 823 and 824, holding rollers 826 disposed downwardly of and in opposition to said respective feed rollers 822, supporting arms 827 for supporting the respective silicon steel plate 50 inserted between the frameworks 821, a link mechanism 829 for turning said holding 826 in the direction of arrow 11 in FIG. 11 by the operation of a hydraulic cylinder 828, a link mechanism 831 for turning said supporting arms 827 in the direction of arrow 12 in FIG. 11 by the operation ofa hydraulic cylinder 830, a stopper means 840 for detaining at a predetermined position each silicon steel plate transferred by said feed rollers 822 and holding rollers 826, a steel plate holder means 850 for holding each silicon steel plate at the stopped position, and a detector 860 which detects ingress of the silicon steel plate 50.  
  Although in the shown embodiment the electric motors 825 are provided one for each of the feed rollers 822, it is possible to provide only one such electric motor to drive all of the feed rollers 822 by use of a chain or like means. In either case, it needs to rotate the feed rollers 822 synchronously to one another.  
  The construction and operations of said stopper means 840 are described in detail below with reference to FIG. 12.  
  The stopper means 840 is mounted at an end of a rod 842 moved vertically by the operation of a hydraulic cylinder 841, said rod 842 being also rotated suitably by the operation of for example an electric motor 843. The steel plate holder means 850 is also mounted at an end of a rod 852 which is moved vertically by the operation of a hydraulic cylinder 85] so as to hold one end of each transferred silicon steel plate 50 at its proper position for lamination.  
  Each of the silicon steel plate 50 transferred into said holder means 820 is first retained between the feed roller 822 and retaining roller 826 and on the supporting arm 827 and is detained by said stopper means 840, and under this condition, one end of the particular plate 50 is held by the holder means 850 and thereafter, the hydraulic cylinders 828 and 830 are operated to turn said retaining roller 826 and supporting arm 827 in the directions of arrows 11 and 12, respectively, allowing the silicon steel plate 50 to drop down as shown by arrow 13 in FIG. 11 to thereby effect lamination of the plates. Upon completion of every such core leg laminating operation, the yoke-forming silicon steel plate 910 and 920 prepared on a bogie 900 are laid in lamination at the upper and lower yoke-laminating positions by manual operations to thereby complete a oneor multi-layer magnetic circuit.  
  FIG. 12 shows the behavior of said stopper 840 in case of constituting a three-legged core in which three core legs are formed from three groups of juxtaposed silicon steel plates 50A. 50B and 50C each of which has been cut aslant at the angle of 45 at both ends. in laminating the silicon steel plate 50A for forming the central leg, each one or every fixed number of said plate is reversed such that the lamination of such plate will be cross-joined at its upper and lower edges with the corresponding yoke portions. For this purpose, such silicon steel plate 50A, when transferred from the bogie 100, are suitably reversed by the reversing means 400. In accordance with alternate reversion of the silicon steel plate 50A as they are laminated, the stopper 840A positioned at the location of the central leg is accordingly reversed 90 in both right and left directions alternately as shown in FIG. 12C. This reversing operation can be practiced by the operation of said motor 843. in this way, the edge of the protuberance 844A of said stopper 840A can securely hold the cut edges of each silicon steel plate 50A to effect correct positioning thereof.  
  Numerals 845A and 846A denote side stoppers for effecting positioning of the silicon steel plate 50A in the lateral directions. These side stoppers are arranged adjustable in size with the respective hydraulic cylinders 847A and 848A.  
  In laminating the silicon plates 50B and 50C for forming the right and left leg portions, each one or every fixed number of said blocks is shifted vertically relative to the other, that is, there edges joined with the upper and lower yoke portions are moved parallel relative to each other and, under such condition, they are laminated together, as shown by B and C in FIG. 2. Therefore, the silicon steel plates 50B and 50C forming the two side leg portions must be moved parallel to each other in the vertical direction in line with the reversion of the blocks A. In order to effect such parallel movement, each of the stoppers 840B, 840C associated with the silicon steel plate 50B, 50C has its protuberance 844B, 844C formed with two parallel edges arranged such that when said stopper is turned one of said edges will be shifted by the amount of said parallel movement relative to the other edge. Thus, these stoppers 8408 and 840C are turned 180 alternately as shown in FIGS. 12B and 12C. Said electric motor 843 can be utilized for effecting such turning of the stoppers.  
  Indicated by numerals 8458 and 845C are side stoppers adapted to effect correct positioning of the silicon steel plates 50B and 50C in the lateral directions. These side stoppers can be adjusted in size by the respective hydraulic cylinders 8473 and 847C.  
  Said stoppers 840A, 8408 and 840C are operated at such positional relation that, at the same laminating position, they will take the postures as shown by (a), (b) and (c) in FIGS. 12A, 12B and 12C, respectively.  
  FIG. 13 shows an example of the laminating pattern in forming the leg portions of a three-legged core according to the present invention. FIG. 13A shows the order of transfer of the respective silicon steel plates Nos. (1) to (6) and Nos. (1&#39;) to (6&#39;), and FIG. 1313 shows the manners in which the reversal instruction, separation instruction and stopper operating instructions are given. Shown in FIG. 13 is an embodiment where two cycles of transfer are formed, the first cycle C, being formed by the blocks Nos. (1) to (6) and the next cycle C by the blocks Nos. (1&#39;) to (6).  
  The respective steel blocks are laminated in the following way.  
  The steel plate No. (l) is reversed in its direction of advancement when transferred from the first conveyor 300 to the reversing means 400 and is parted to the right (R) by the pin 730 in the parting or separating means 700. During this period, the stopper 840B (indicated by 11 in FIG. 13) of the core stacking mechanism 800 is retained at the position a) in FIG. 12B. The next steel plate No. 2) is not reversed and parted to the left (L) by the separating means 700. During this time, the stopper 840C (indicated by 111) of said core stacking mechanism 800 is maintained at the position (a) of FIG. 12C. The steel plate No. (3), which is transferred next to said plate No. (2), is neither reversed nor parted and allowed to advance straight forwardly, and the stopper 840A (indicated by l) of the core stacking mechanism 800 is retained at the position (a) of FIG. 12A. The still next silicon steel plate No. (4) is reversed by the reversing means 400 and parted to the right side (R) by the parting means 700. At this time, the stopper 840B (11) is switched to the position (b) of FIG. 12B,  
  causing parallel shifting of the laminating position relative to the No. 1) plate. The immediately ensuing plate No. (5) is not reversed but parted to the left side, and the stopper 840C (111) is switched to the position (b) of HG. 12C to effect parallel shifting of the laminating position relative to the No. (2) plate. The steel plate No. (6) that follows said No. (5) plate is reversed but not parted, with the stopper 840A (1) being switched to the position (b) of HG. 12A, allowing lamination of said plate with its both edges crossed relative to the No. (3) plate.  
  FIG. 14 shows another example of the laminating pattern for forming the leg portion of a three-legged core. in this example, only one cycle C, is formed by the plates l) to 12). in the laminating pattern shown in FIG. 13, the steel plates are laminated by shifting each of them relative to the other, while in the case of FIG. 14, the plates are laminated by shifting every two pieces relative to the other (every two pieces being laminated at the same position). The details of such laminating pattern are explained in H0. 145.  
  While the foregoing discussion has been devoted to the explication of the laminating patterns for assembling a three-legged core, it will be understood that, in forming a two-, fouror five-legged core, the operations of the reversing means, parting or separating means and stoppers of the core carrier means can be all regulated into systematic patterns to permit automatic block lamination for forming the leg portions of such core.  
  Also, although there have been shown embodiments where the steel plates are laminated by shifting each or every two pieces of plates relative to the other, it is possible to practice lamination by shifting every three or four or more pieces relative to the other.  
 We claim:  
  I. A method of producing a laminated magnetic core for use in an inductive electric apparatus, the core having leg portions and yoke portions magnetically connecting the ends of the leg portions. the leg portions as well as the yoke portions are formed of silicon steel plates which have been cut into predetermined configurations, the core being formed by laminating the leg portions as well as the yoke portions in a predetermined order, said method comprising the following steps:  
 a. stacking on a support board a plurality of silicon steel plates for forming the leg portions ofthe core, said plates being piled up in the order converse to the predetermined order of lamination;  
 b. delivering to a parting or separating mechanism said silicon steel plates stacked on said support board one by one successively from the topmost one of said stack;  
 c. parting or separating said plates in substantially parallel relation and at fixed intervals so that the longitudinal direction of said plates will correspond to the respective positions of the leg portions in the core;  
 d. transferring said separated silicon steel plates successively and in a given order in their respective leg positions to a core stacking mechanism which is lowered correspondingly to the number of layers 12 forming the lamination;  
 e. magnetically connecting the corresponding edges of the respective leg portions transferred onto said core stacking mechanism by joining said edges with the corresponding edges of the separately prepared silicon steel plates forming the yoke portions; and  
 f. integrally combining and fastening together said respective leg portions and yoke portions, both the leg portions and the yoke portions having been laminated on said core stacking mechanism in the above-said steps, by use of suitable fastening means through the media of supporting plates.  
  2. A method of producing a laminated magnetic core for use in an inductive electric apparatus, the core having leg portions and yoke portions magnetically connecting the ends of the leg portions, the leg portions as well as the yoke portions are formed of silicon steel plates each of which has been cut aslant at its both ends, the core being formed by laminating the leg portions as well as the yoke portions in a predetermined order, said method comprising the following steps:  
 a. stacking on a supporting board a plurality of silicon steel plates for forming the leg portions of the core in an order converse to the predetermined order of lamination, said plates being arranged such that the cut edges at both ends will be of the same direction;  
 b. delivering to a reversing mechanism said silicon steel plates stacked on said supporting board one by one successively from the topmost one of said stack;  
 c. reversing the front side back according to a reversing instruction, transferring the reversed silicon steel plates and the non-reversed blocks successively in turn;  
 d. separating said transfered silicon steel plates in substantially parallel relation and at fixed intervals successively in a given order such that the longitudinal direction of the plates will correspond to the respective positions of the leg positions in the core;  
 e, transferring said separated silicon steel plates successively in their respective leg positions to a core stacking mechanism which is lowered accordingly to the number of layers of the lamination;  
 f. magnetically connecting the corresponding edges of said respective leg portions transferred onto said core stacking mechanism by joining said edges with the corresponding edges of the separately prepared silicon steel plates forming the yoke portions; and  
 g. integrally combining and fastening together said respective leg portions and yoke portions laminated on said core stacking mechanism in the above-said steps, by use of suitable fastening means through the media of supporting plates.  
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