BE478848A - - Google Patents

Description

       

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  NEW SHEET CORE CONSTRUCTION PE1CEDE'l'l !: 3 FOR .rIPPAILS ELEC'I'BJ1-? TfA.GNETIQ1J1! 'S A INVL3I6Nb
The present invention relates to a new method of constructing laminated cores, of the curved type, for electromagnetic induction devices,
Until now, it was customary to constitute Induction electromagnetic devices, such as transformers and reactance coils, with cores belonging to two main types: one being the type with stacked sheets. flat, each layer comprising a number of such tales, cut to the required size and shape, the other being of the folded or coiled type, in which the magnetic strip forming the core is folded or bent over the plate to form a number of bundled sheet layers.

   There is still a
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 third type in agglomerated iron powder, which has parbieuliéreµ * n4 applications in high frequency devices.

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   Although the construction of cores of the flat-folded type has been known since the latter part of the last century, as shown, for example, in British Patent No. 7856 of 1889, for many years it has been conventional to form the cores of electrical apparatus. magnetic induction by assembling a number of bundles of cut flat sheets to form a closed core, These sheets have been cut into various shapes, for example '1-shaped cut sheets that overlap at the four corners, or cut sheets L-shaped and assembled two by two inverted to form each layer from core to core. closed magnetic circuit *
However,

   When sheets with a high magnetic directional effect were made available to technicians and constructors of transformers, it was quickly noticed that cores formed from a certain number of layers of sheets of this new steel, and overlapped by their corners, are affected in the region of the corners of higher losses due to the fact, that the flux must pass perpendicular to the most favorable magnetic direction *
Attempts to overcome this difficulty in flat stacked sheet cores have taken advantage of the idea of cutting sheets with diagonal ends and then welding these elements together to create at angles in the line flow path with the most favorable magnetic direction.

   Another arrangement provides a miter lap joint at the corners so that only a minimum of flow is forced to pass through the most favorable direction.



   When placing the winding on a folded or wound core, care must be taken that the sheet metal strips are not bent beyond the elastic limit, in order to keep the core efficient, because the bending or any effort beyond a predetermined value greatly increases losses.



   The method generally employed comprises the detrimental steps: a strip of sheet metal is wound on a mandrel of the same shape as the core must have when it is in place in the finished apparatus; then the core is annealed in this state. The core is then unwound and simultaneously rewound around a preformed coil so that each sheet of the finished core has the same shape and the same relative position with respect to the others sheets than that which it had ap reed the annealing, The described process gives a circular core
In another method, a spirally wound core is then deformed such that it can be associated with a coil of elongated or rectangular cross section.

   This second method can be employed with a continuous strip of sheet metal, or by cutting the strip at each pair of turns during its winding or threading in the window or opening of the reel.

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   As the two methods cited above involve the threading of the annealed magnetic tape, through the opening of the reel, without the flexion of the tape exceeding the elastic limit, these methods have found their most economical application in types of small-size transformers, such as those for current distributions, in which the strip is of such size that it can be easily handled,
The present invention relates to a new method for constructing cores of the curved type, with magnetically oriented steel t8les capable of being associated with coils prepared in advance on form. This method is simple and aims to produce devices. induction with good efficiency for both circular and non-circular cores conformations,

   and for a relatively wide range of device sizes,
The new process is in particular oaractérisé, in that the t8les, intended to constitute the core, being previously cut to the required dimensions, from strips of steel sheets whose optimum magnetic orientation coincides with the longitudinal axis of the strip, these cut and grouped sheets are then bent or bent by any appropriate process of mechanical stress (pressure or expansion) to the shape required to constitute a magnetic circuit which is closed, optionally by one or more intermediate pieces, by stop joints , overlapping, or interlocking, etc., .., or by a combination of such joints,

   the mechanical stress undergone by the sheets during bending or bending then being eliminated by an appropriate annealing and the constituent parts of the core being finally assembled on or around the pre-built winding coil.



   With reference to the appended schematic figures and, by way of nonlimiting examples, various arrangements for direct implementation of the invention will be described below. These embodiments should be considered as forming part of the invention, it being understood that any equivalent arrangements could just as easily be used without departing from the scope thereof.



   In the given figures applications of the invention have been shown to transformers, but it should be understood that the invention can be applied to any other type of electro-magnetic induction device, such as a reactance coil,
Referring to the accompanying drawings, Fig, 1 shows an electromagnetic induction apparatus, such as a transformer, comprising a conductive winding and curved iron type cores constructed in accordance with the invention; Fig. 2 is a perspective view of the stacks of the three different groups of sheets

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 magnetic used to constitute the cores of the curved type of Fig.l; the
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 Fi.3 is a perspective view of an apparatus which can be used during the manufacture of a core of the type shown in Fiq.1;

   FIGS. 4, 5 and 6 represent various stages of a process for assembling the three groups of FIG. 2; the
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 Fig, 7 is a perspective view of the torus-shaped core placed around an expansion mandrel; Fig. 8 shows the configuration of the core of fig. 7 after it has
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 been stretched into an elongated or rectangular shape; rîc.9 represents in a somewhat schematic way a number of core elements placed in a furnace for
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 undergo annealing and eliminate internal stresses atnai;

   Fig. 10 is a side elevation and sectional view of the transformer of Fig. 1, with one of the cores of the curved iron type assembled on one of the rectilinear portions of the coil and with a second core being assembled through the opening or window of
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 the spool and around the other leg of the spool; Figolls and 12 represent the invention applied to a core constructed in the shape of a cross; FIg.H is a perspective view of a three-phase transformer using three cores in accordance with the invention; Figs. 14 & 15 show a transformer having a circular window coil and four cores constructed in steps; Figs. 16, 17 & 18 show the invention applied to a core with a stop seal;

   Fig, 19 shows a core constructed in accordance with the invention, assembled with the coil, this core
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 having a circular shape instead of being stretched oblong! Flgb2O shows a transformer of the type of Fig. 1 having a differently constructed joint; the
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 Fig.21 shows in more detail the construction of the seal of the core of the pig, 2 before being stretched; Figt28 represents the nucleus of Fig.21 after having been Attr6, - Flg.23 to 26 represent particular features of the invention applied to a modified construction of the nucleus; and Fig. 27 is an enlarged view of about three of the sheet layers of Fig. 23 in the vicinity of the joint.



   Fig. 1 of the drawing shows a transformer comprising a coil 20 with a non-circular or oblong opening, or window 21. Through approximately half of the window 21 of the coil and surrounding one of the rectilinear parts or legs 20, a magnetic core 22 is passed. In Fig. 1 a similar core 23 is shown filling the other half of window 21 and surrounding the other rectilinear part of the coil.

   It should be understood, however, that only one or any suitable number of these advanced Curved iron cores may be used,
When associating a core with a previously constructed type of reel, it is necessary, as noted above, that the magnetic tape
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 tick is not bent beyond its elastic limit, otherwise its magnetic properties ¯, - L-

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 - ticks will be considerably reduced.

   As shown in the drawings and described below, the invention provides a method of assembling a core of the curved iron type to produce, with a pre-built coil, an efficient structure which not only, does not bend the magnetic tape beyond its elastic limit, but at least part of the magnetic core is assembled through the opening of the pre-fabricated coil without having to bend or move gathered sheets very tightly in this part of the nucleus.



   In the transformer shown in Fig.l, each of the cores 22 and 23 comprises a U-shaped portion 24, and a curved portion or yoke 25. The portion 24 of the magnetic core is formed by a group of t8les designated with a generally by the number 26 in Fi.2. The removable cylinder head 25 comprises a group of sheets represented by the number 27 (Fig.2).



   The cylinder head of Fig, 1 comprises a number of filler bands of the group designated generally by the numeral 28, but in the remainder of the description it will appear that the filler bands 28 can be omitted, if it is necessary. longed for.



   Although some features of the improved method, as described below, of constructing a core of the curved type, can be used to form a core having a seal placed at any suitable part of the core. , it will be seen in the construction shown in Fig. 1 that the adjacent ends of the various sheets are, at one end of the portion 24 of the core, in alignment with the interior surface 29 of the rectilinear portion of said core, while the other ends of the sheets forming the portion 24 of the core are in alignment with the other inner edge of the rectilinear part.

   In this way the portion 24 of the core is U-shaped with its ends in the same general planes as the inner and outer surfaces of the rectilinear or columnar part, so that the gap between the opposite ends of the t8les constituting the part 24 is at least roughly equal to the thickness of this colons of coil 20 which is surrounded by core 23. With such a construction, the U-shaped portion can be assembled with the coil without bending the sheets. nor move the ballot boxes in relation to others. The special construction of the seal will be described in more detail below in connection with Fig. 10.



   In order to constitute a packet of cut sheets 26 to form part 24 of the core, in which the sheets will have the relative lengths shown in Fig. 1, the elementary sheets forming the group 26 are provided such that

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 those which will be at the inner periphery of the finished core have a predetermined length, and that these sheets have progressively increasing lengths going towards the outer periphery.

   Thus, knowing the slowness of the inner and outer contours of the core and the thickness of the latter, it is possible to determine with some precision the exact length that the sheets must have in order to achieve the desired joint construction and the sheets. can be calibrated and cut by hand, or else be cut on a register index shearing machine and which will be described in detail below.



   The different groups or bundles of sheets shown in Fig. 2 can be assembled in any suitable manner to form the improved core and there is shown in Fig. 3 a suitable device by means of which the sheets can be assembled to accomplish a stage of improved process.



   Fig. 3 shows the device which comprises a construction composed of bands 30 and 31 in the form of rings, these bands being supported on one side of the ring by a fairly rigid support part 32. The rings 30 and 31 have ends which can be attached to a block part 33, the other ends being fixed to a relatively movable part 34. The space remaining between the ends supported by the blocks 33 and 34, is completed by ring segments 35 and 36 which cover the ends of rings 30 and 31.

   Movable bars 37, 38 and 39 are provided with curved faces to cooperate with the sheets when they are inserted into the machine of Fig.3 to group them as described below. The bars 37, 38 & 39 are attached to rods 40, 41 & 42 respectively, which are radially movable, and which, when they are moved outwards as indicated by the arrow, apply pressure to the assembled sheets. to form them into fairly tight bundles, or group them together.

   It can be seen that the blocks 33 & 34 are relatively mobile so that the circumference of the rings 30 & 31 can be contracted in order to tighten the adjacent ends of the sheets of each layer quite strongly, which will also be described in more detail below. .



   Referring to Figs. 4, 5 & 6, it can be seen that the sheets of the various groups shown in Fig. 2, can be assembled inside the rings 30 & 31 in any suitable manner so that the adjacent ends in two of the groups come into the stop position and the two groups constitute a closed magnetic core Thus a sheet of the longest group 26 and a sheet of the shorter group 27, of sufficient dimensions, are assembled to form a layer

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 complete around the circumference of the core, although they may have any other suitable length, In another state of the art of the improved method shown in Fig. 4, one of the sheets,

   for example that indicated by the number 45 of the smallest group 27 of Fig. 2, is introduced inside the rings 30 & 31, then the longer sheet, indicated by the number 46, of the group 26, is introduced to inside the ring, so that, when the core has taken the shape it should have in the finished apparatus, the ends of the adjacent sheets 45 & 46 are end to end or in the stop position, as shown in Fig. 6.

   For ease of assembly, the sheet 46, when first inserted by hand, is not sufficiently bandaged for its ends to abut against those of the sheet 45, however this is done when a suitable number of sheets have been assembled, applying tension to the parts 37, 38 & 39, but it should be understood that each sheet can be placed separately, if desired,
In order to continue the assembly of the sheets of the two groups, a second sheet 47 of group 27 can be introduced in / same part of the rings as that occupied by the sheets 45, and the next sheet 48 of group 26 is placed adjacent to the sheet 46.

   After a suitable number of sheets have been introduced in the manner described above, a filler sheet 49, from group 28 of Fig. 2, can be placed and the purpose of this fur 49 will appear in the following. of the description.



   To facilitate the retention of the various sheets in the rings 30 & 31, rods 50 & 51 are provided and openings or holes are made in the various sheets through which relatives can pass. Thus, the pins 50 & 61 extend in diametrically opposite directions in stacking rings 30 & 31, and spindle 51 is provided to pass through all the holes 32 provided in the sheets of group 26, Likewise holes 53 & 54 are provided in groups 27 & 28 , holes through which the rod 50 extends, these openings being visible in Fig. 2,
After the correct number of sheets from the various groups have been inserted into the stacking rings or circles 30 & 31, pressure is applied to the three rods 37,

  38 & 39 to force the assembled sheets to push outward and extend over a perimeter a little larger than the final perimeter of the finished core, so that the ends of all adjacent sheets take their correct position. This position is shown in Fig. 5, the

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 adjacent ends of the sheets donating two groups being slightly apart. Then a force will be applied to the block 34, keeping the block 33 fixed, in order to
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 pull the periphery by bringing the ends of the rings 30 & 31 closer together, until the ends of the sheets of each layer are placed end to end, as shown in Fig.6.



     It can be seen that the finished core, shown in Fig, 6 as well as in Figs. 1 & 10, has an offset stop joint, so that adjacent joints of layers contl-
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 gizës do not match. To achieve a proper arrangement of the offset stop joints, the holes in the groups of plates 26 & 27 are placed with a slight offset5ar from the longitudinal center of each elementary plate, as shown in Flue, .2, la value of the offset determining the value of the overlap of each of the adjacent ends.

   When assembling the sheets, the adjacent sheets in each group are turned over so that the longer sheets, extending from the eccentric hole, go first in one direction and then in the opposite direction from the spindle 51. Holes 51 & 53 can be made at any time and the Applicant Company has found it more convenient to punch the hole at the same time as the sheet is cut on the machine.



   Referring to Fig. 4, the lap joint is obtained as follows: the first sheet 45 is introduced by passing the rod through the hole 53 and placing the longer side of the sheet 45 in one or the other direction, by
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 example to the left of pin 5cob -as visible in Fig, 4.

   It is obvious that the sheet 46 is to be placed with the pin 51 passing through its hole 52 with the shortest dimension also extending to the left of the pin 51 so that the adjacent ends of the sheets 45 & 46 are placed in position. stop when they are
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 in the situation shown in Fig.6 ,, Referring to this Flg.6, the joints between the poles 45 & 46 will thus be moved to the left by an amount equal to the exeentra '? e of the holes 52 & 53 relative to the longitudinal axis of the respective sheets.

   In order that the stop gasket between adjacent ends of ttles 47 & 48 is offset from the right of pin 5 (, these plates will be placed on pins 50 & 51 with their longer parts extending into the direction opposite to that given to sheets 45 & 46, that is to say to the right of the pins,
It will be understood that when the various plates 45, 46, 47, 48 are assembled as described above, any number of plates may, of course, be employed.

   For example, a sheet of a group can be assembled alone with a sheet

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 of the other group or any suitable number can be assembled and the Applicant Company has found that by employing strips of sheets about 0.3 mm thick it is convenient to join the various sheets together. groups of two in each of the groups, so that there will actually be two stop joints in line, these joints being offset from adjacent joints.



   Construction with a stepped stop gasket, or stop-and-lap joint, is more efficient from a performance point of view than if the holes were placed in the middle of the length of each plate so that all seams fit. do not go online. However, an assembly made in the latter way can, of course, be achieved by the improved method, object of the invention, if desired, a construction of this type being shown in Figs. 16 to 18.



   In order to provide, in suitable places of the core, a continuous path for the flow which passes through the two series of joints, filling plates or linings 49 have been provided. These linings 49 obviously increase the cross section of the removable yoke 25, compared to the remaining part 24 of the core, by an amount equal to the total thickness of the furring strips 49. For example in the construction shown in Fig. 6, where four 0.25 mm furring strips were employed, the removable part 25 will be about 4 x 0.25 mm thicker than the rest of the core, or the part 24. It will of course be understood that the liners can be omitted, if desired. As the ends of the furring strips 49 are not in abutment position with other sheets, the perforations 54 can be placed in the center of the sheets.



   After assembling the sheets, as shown in Fig. 6, and in order to achieve an elongated core shape, the assembled sheets are removed from the assembly apparatus of Fig. 3 and lengthened in any suitable manner. To ensure that the sheets after their removal remain held in the assembled position, a strip 60 of a suitable material such as metal can be placed around the assembled sheets to hold them. This strip can be placed around the assembly of the sheets in any suitable manner and, in Fig. 6, it will be seen that the strip 60 has been wound around the assembly in the gap between the two spaced rings 30 & 31 .

   One end 61 of the strip can be positioned so that there is an overlap, so that when end 62 is attached to the rotary device 63, the strip 60 can be clamped quite tightly around the assembled sheets. The strip can then be closed by welding, as indicated by the numeral 64, after which the end 62 can be detached from the device 63 and the excess of the strip cut off.



   The core can be lengthened by any suitable method using by

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 example an expandable mandrel which includes two blocks 65 & 66 with inclined surfaces (Fig. 7 & 8). By introducing a wedge 67 between the inclined surfaces 65 and 66, the
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 Sheets will be made to take the shape shown in the die. 84 Pin 68 is then inserted through hole 69 in wedge 67 to hold the expandable mandrel in
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 the position indicated by F1g, 8, It will be understood that the expandable mandrel is of a size and shape such that the entire core, as shown in
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 the Fiq, 8,

   will take a shape similar to that which it must have in the finite nucleus as represented Fâg.lo
In order to fix the sheets in their proper and relative position which they must have in the finished apparatus, as well as to eliminate the harmful tensions, the assembly shown in Fig. 8 must undergo an annealing removing these tensions. sions. This can be accomplished by any suitable means, such as, for example, by assembling several cores in an annealing furnace as shown schematically.
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 on 7.a FigA9 'and heating to a suitable temperature, around 98t C, for a time sufficient to give the core the desired annealing,
After removing the cores from the oven.

   they will have taken their final position, and the tensions due to the expansion and bending of the sheets will have been eliminated. The core is then in the conditions desired to be assembled with the coil wound in advance on the form.



   To assemble the core after removal from the oven with the preformed coil
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 as shown for example in Figtl, the movable yoke is removed and leaves a U-shaped portion which can be introduced into the opening or window of the preformed coil, Referring to Fig. 10, it will be seen that, on the right side of this figure, is shown a core with the cylinder head 25 removed and the part 24 in
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 U of the core introduced into the window of the coil.

   The oulas 25 may be removed by applying pressure to it in the general direction of the plane of the sheets. Any suitable quantity of these removable sheets, among those which constitute the
 EMI10.7
 groups 27 & 8, will be removed at the same time; we will apply pressure to pull all the sheets of the cylinder head together at the same time, they can also be taken out in small groups, While removing the sheets from the cylinder head, it will be necessary to have
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 care must be taken to arrange them in the order in which they will have been removed, so that after the core portion 24 has been introduced into the coil, they can be put back in the place which each sheet occupied in the yoke before its removal.

   The Applicant Company has found it convenient to remove 10 to 12 sheets from each yoke.
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 to the liver when using sheets of about 0.35 wun, starting with the sheet

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 outside and stacking them so that when they are all removed, the inside sheet is on top of the stack.

   The sheets can then be reassembled in any convenient way, for example by holding them all in their correct alignment and inserting them either all together or by a small number such as 4 or 5, both starting with the smaller (or the most inside), and inserting them in their correct location, When all the yoke plates 25 have been thus introduced, the sheets of the core will have resumed the positions they had before annealing, and surround the rectilinear portions of the coil in the position shown in Fig. 10.



   The Applicant Company has found that an electromagnetic induction device, such as a transformer, constructed in the manner described above, gives a very good efficiency core and furthermore has a very large space factor. By "high spatial factor" we mean that as much iron as possible is contained in the window of the coil, and it will be appreciated that the more iron can be placed in the orifice of a given coil. , the smaller will be the surrounding winding and the complete apparatus, required for a given number of KVA.

   Referring to Fig. 10, it will be seen that the core parts 70 and 71 surrounded by the coil are placed quite tightly in the opening of the coil with just enough free space between them to allow part 71 to be put in place after part 70 has been assembled around the spool. Further, since the U-shaped portions 24 of the cores were no longer disturbed after the stress relieved by the annealing, the portions 70 and 71 remained relatively loose.



  This is particularly visible by referring to Fig. 9 where it will be noted that these parts are arranged one above the other and that a weight 72 is placed above all the cores as well during the annealing which is made at a temperature sufficient to soften the steel but not high enough to make it flow, the adjoining sheets in parts 70 & 71 will be pressed quite strongly against each other and, due to the construction and method improved assembly, the sheets which constitute parts 70 & 71 are in no way disturbed or moved relative to each other during coil assembly. On the core, of course, they could be bent slightly if necessary or desirable.



   In order to show the efficiency of an electric induction device constructed in accordance with the invention, the excitation current in ampere-turns per cm, and the losses in the core, have been indicated below in the following table. in watts per

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 Kg. At densities in the straight parts or legs, varying from 1.56 to 18.8
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 kilolines per square cm:

   
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 <tb> Density <SEP> current <SEP> of excitement <SEP> losses <SEP> to <SEP> kernel
 <tb>
 
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 in Kilolines in A.T. per cm in watts per Kg
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 <tb> 1,560 <SEP> G, 075 <SEP> 0.025
 <tb>
 <tb> 3.120 <SEP> 0.12 <SEP> 0.09
 <tb>
 <tb> 4,700 <SEP> 0.16 <SEP> 0.19
 <tb>
 
 EMI12.5
 6j2Go Gi, 183 0.32
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 <tb> 7,800 <SEP> 0.242 <SEP> 0.484
 <tb>
 <tb> 9.40G <SEP> 0.296 <SEP> 0.68
 <tb>
 <tb> 10,900 <SEP> 0.372 <SEP> 0.91
 <tb>
 
 EMI12.7
 18.500 0.482 1.2 14, CGD 0.68 1.54
 EMI12.8
 
 <tb> 15,600 <SEP> 1.17 <SEP> 2.08
 <tb>
 
 EMI12.9
 17.00C! 2.79 2.78 18.8m.

   8.8 4.34
 EMI12.10
 In itZigo 1 to lu, the invention is described as applying to a single coil with a rectangular opening or window, but it should be understood that
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 the invention can be used with any model of coil and any type of corresponding core.



  Figures 11 to 15 show other types of electromagnetic induction apparatus in which the improved core construction finds effective application, but it should be understood that these types are indicated only as a guide. examples and in no way limit the types to which the invention can be applied *
In Figs. 11 & 12, there is shown a construction comprising a core intended to fill the tubular (cylindrical) opening of the coil 75 previously constructed, two similar cores 76 and 77 being shown, each of them being constituted by three separate portions, to three different widths.



   The inner section 78 is assembled first around the core and then the section 79 whose sheets have a greater width is assembled second. A final section 80 is provided, with a width of the sheets slightly smaller than the diameter of the coil opening. The sections of the core can also be assembled into a single unit It will be understood that the core 77 has sections similar to those of 76 so as to constitute a cross-shaped core, which fills the window of the coil in a more complete manner. than a rectangular core. Each of the two cores is constructed as described above.
 EMI12.12
 



  In Fig. 13 there is shown a perspective view of an electromagnetic induction apparatus having three separate cores associated with three coils, this construction having its particular application in a three-phase transformer.

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  It is seen that the construction includes three coils 85,86 & 87, with a core 88 passing through the windows of coils 85 and 86, and a section of core passing through the windows of coils 86 & 87. A third core 90 surrounds the coils. cores 88 & 89 and passes through the windows of coils 85 & 87, The cores shown in Fig. 13 are also constructed in the manner described above
Figs, 14 & 15 show another method for lining a circular or tubular shaped window or coil opening, by means of four different cores, each having two different widths.



   As can be seen in Figs. 14 & 15, a coil 95 having a tubular shaped opening or window is surrounded by four different cores 96,97, 98 & 99, As these cores are all similar, no description will be given. only one. The core 96 is made up of a part 100 having a certain width and built up to a certain dimension depending on the size of the window of the coil. A section 101 is then placed around section 100 and made of magnetic sheets having about half the width of section 100. Four cores so constructed can be assembled with a coil, by first assembling a section. 100 then surrounding it with the narrower part 101, as can be seen in Fig, 15.

   The ridge of the core portion 101 is located relatively close to the outer sheets of the larger core portion 100.



   In Fig. 16, there is shown a core construction similar to that of Fig. 1, except that there is provided a stop seal between the two portions of the core or else an offset seal, as it is. described above with reference to Figs, 1 to 10. The core comprises a U-shaped portion 100, and a removable portion 111 or yoke, with stop seals 112 & 113.

   The parts 110 & 111 are formed by sheets coming from two groups in the same way as described above, with reference to Fig.2. The U-shaped portion of the core 110 is constituted by a group of sheets having a shape identical to that indicated for the group 114 in Fig. 17, while the removable yoke consists of a stack of sheets 115 in Fig, 17 . Note that groups 114 and 115 have openings 116 & 117 which are located in the middle of the length of the sheets, so that when they are stacked as described in connection with Figs. 3 to 6,

   the joints between the adjacent sheets of each group will face each other as shown in Fig. 18. The core can then be lengthened to form a part having the arrangement shown in Fig. 16, or, if desired, the

  <Desc / Clms Page number 14>

 
 EMI14.1
 core can be used in its circular shape, as shown in Fig. 184 It will be understood that the construction of the core of Figs. 16 & 18, unless done with great precision, will have losses in the iron and in excitation current a little
 EMI14.2
 higher than the staged joint core of the Fî .1
In FIG. 19, an electro-magnetic induction device has been shown having a core 120 associated with a coil 121.

   The core 120 is similar to that shown in Fi.6 and is used without undergoing the lengthening operation which has been em-
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 bent to produce the core of Fig. 1, The core is assembled with a preformed coil, removing the removable yoke 122, threading the core through the window of the reel 121, and finally reassembling the yoke parts 122 in the manner described above.
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  In Fig. 20 there is shown a transformer having cores formed in the manner described above with respect to Figs. 1 to 10, except that the various sheets have been cut to produce a stop-to-lap joint as shown.
 EMI14.5
 qué in Fig * 21. Since each of the cores 123 & 124 is similar to the other, only one will be derlt. Flgt21 shows the nucleus formed by the assembly of tales of the two groups similar to groups 26 & 27 in Fig. 2. However, in the construction of Fig2, the two groups of sheets used to produce this core are cut in such a way that the corresponding sheets of each group which constitute a complete layer have a total length slightly greater than the periphery, of that particular layer.

   This produces in the removable portion
 EMI14.6
 of the breech ', an additional slowness. Thus the core 123 of Fig.2 (is formed of a part 125 and a part 126 of the dismountable yoke. The core is assembled by abutting one end 127 of a sheet 128 of the yoke with an adjacent end. a sheet 129 taken from the longest group of similar sheets
 EMI14.7
 to those of group 26 of Fig, 2. The sheet 129 is, however, long enough for its opposite end 130 to cover the adjacent end 131 of the sheet 128.

   Likewise a cylinder head plate 132 is formed with a stop gasket against the adjacent end 133 of the plate 134 of the longer group of plates. There again the
 EMI14.8
 Plate 133 is long enough that its oppQrsêed end 135 overlaps the adjacent end of the cylinder head plate 132 * This particular lapped stop gasket will produce a construction about one and a half times the thickness of the rest of the core.



   After the sheets have been assembled, as shown above about
 EMI14.9
 of Fit.21, the core can be used in this form after annealing, where it can be lengthened as shown in Fig22, Due to the extra thickness of the portion 128 of the cylinder head, this portion will have voids and, if desired , a warning

  <Desc / Clms Page number 15>

 can be made in the part having the voids by means of a wedge 136 embedded in the yoke, to receive part of the turns of a coil. After the core has been annealed in the shape shown in Fig. 22, the elongated portion and wedge 136 can be removed.

   In the construction described above, the cores each have the shape of a U-shaped part with a removable part or yoke, but it should be understood that the characteristic features of the invention can be employed to constitute a core provided with a joint located in any other place of the periphery, and in Figs. 23 to 26 there is shown a core with a stop point and overlap placed in the rectilinear parts of the cores and columns. The core 23 comprises the two U-shaped portions 140 & 141, the portion 140 being formed of a group of sheets indicated in Fig. 24 by the numeral 142, the U-shaped portion 141 being formed of a group of sheets 143.

   As can be seen in Fig, 24, an overlap is provided by making openings 144 & 145d in the group of plates, these openings being eccentric with respect to the longitudinal axis. In this way, when the sheets are assembled in the manner described above in connection with Figs. 3 to 6, the corresponding sheets of each group serving to form each layer will be in the abutment position, but the adjacent sheets of the layers have staggered joints.



  This overlap will be produced by turning the t8les of the two groups over as described above. with reference to Figs. 3-6. The core can then be elongated to a rectangular shape and then be annealed in that state. The U-shaped portions can be separated by applying forces in opposite directions to the two U-shaped portions, so that the U's are separated, as shown in Fig. 26.



  The two U's can have their rectilinear parts reassembled in a coil window by pushing them into each other in a direction parallel to the longitudinal axis of the core, or perpendicular to the plane of the sheets. As the sheets of the construction of Figs. 23 to 26 are cut so that the joints fit in the straight parts or legs, the portion 141 must be joined with the portion 140 by inserting the sheets in a direction parallel to the longitudi- nal axis of the core, instead of inserting them in a direction perpendicular to this axis, as in the method of assembling the removable yoke 85, with the U-shaped position 24 shown in Fig.10.



   In order for the ends of the U-shaped portions 140 and 141 to be stiff enough so that they can fit together properly, a number of sheets will be used to form each layer of the core, although a sheet may be used in each layer. of sufficient thickness, if desired. So a

  <Desc / Clms Page number 16>

 layer 146 of the core portion 140, could be formed of three sheets of approximately 0.25 mm, With a single sheet of 0.25 mm, the end of the layer 146 would not be as stiff as using three sheets , so that more tenaps would be required to fit the tip of the layer 146 into the gap between the tips 147 & 148 of the adjacent layers of the core portion 141.

   However, any suitable number of sheets may be used in each layer provided the protruding ends are stiff enough to fit together in the correct position. In Fig. 27, three adjacent layers are shown enlarged to show the stepped arrangement of the joint when three sheets are used to form each layer.
In order to produce the bundles or groups of sheets which serve to form the whole of the core described above and shown in Fig. 2, the cutting of suitable sheets or magnetic strips, with a large magnetic direction along their longitudinal direction, can be done in any suitable way.

   As mentioned above about Flg.2, starting from the dimension. of the opening of the coil, the builder can calculate, knowing the average width of the magnetic tape to be used, the number of layers which will go into the constitution of the core, and he can determine the length of the sheets according to the - right where the joint must be placed, Thus two groups of cut strips can be produced to constitute a stop joint in the two rectilinear column parts, as in Fig. 16, and we will not lose sight of the fact that in the realization of 'a stop seal,' a seal of a certain precision should be obtained in order to have low losses in the iron., There is a method of manufacturing the core so as to obtain a stop seal of a certain precision in the danger of seizing,

   which would cause short circuits, which should be removed by suitable treatment, as is well known in the practice of transformers and motors,
It can therefore be seen that any type of stopper joint, straight, or sling, or overlapping, can be produced after simply having cut the various groups of sheets to the desired dimensions, which can be achieved either by hand or by means of a special machine of the kind that we will describe,
This machine is used to cut all kinds of materials into strips at progressively increasing lengths and allows one or more holes to be punched simultaneously at marked locations along the length of the cut strip.

   It is therefore particularly suitable for cutting sheets used for

  <Desc / Clms Page number 17>

 making the magnetic cores which are the subject of the invention,
The peculiarities which characterize this machine will emerge from the description below with reference to Figs. 28 to 31 and it will appear that said machine constitutes an important part of the invention,
Fig. 28 shows a side view of the cutting machine constructed in accordance with the invention; Fig. 29 shows in elevation a stack of sheets cut to progressively increasing lengths by the machine of Fig. 28; Fig.30 is a perspective view of the parts of the machine, and Fig.31 is a view on a larger scale of the punch used on this machine.



   Referring to Fig. 28, it can be seen that the machine comprises a support-forming table 210 provided with feet 211. On the table 210 is installed a member 212 with a flat surface on which a strip 213, which must be cut and punched, can be placed. The web 213 can be fed to the machine in any suitable manner, and in Fig. 28 can be seen a roll, from which the web 213 unwinds.

   The strip 213 can be metal or other material, and the Applicant Company has found that the improved divider cutting machine is particularly useful for cutting parts from magnetic steel strips 213 used in construction. of cores for electromagnetic induction devices, Rollers 215 and 216 serve to flatten the strip 213 and to remove any burrs on the strip.



   The group of tiles 217 (Fig. 29) is made up of elements of progressively increasing lengths: piece 218 at the bottom of the stack being the longest and piece 219 at the top being the shortest. The pieces are stacked with their corresponding axis lines, indicated at 220. It will also be noted that holes 221 are punched in each of the pieces, with the same offset in each piece relative to the center of this piece. A group of magnetic sheets 217 will be employed to form a core portion of the types described in the present invention.

     This machine will be described for cutting strips of sheet of gradually increasing length and punching the hole placed in each sheet in the relative position shown in Fig. 29, it being understood that the machine can be used to perform any other group. - ment of strips of material having suitable relative lengths and with holes placed in any suitable position of each of the strips.



   The machine comprises a knife 222 movable vertically from the surface of the base 212, or towards this base, or away from said surface. The

  <Desc / Clms Page number 18>

 knife 222 is supported by a relatively stationary support 223 within which the knife can move vertically. In order to punch a suitably placed hole in the part while it is being cut from the strip by the knife 222, a punch indicated as a whole by the number 224 is installed.



  Any type of punch suitable for the intended purpose can be employed and, in Fig. 31 there is shown a particular type of punching machine which comprises a punch 225 carried by a piece 226 forming a support. In order to adjust the length of the metal strips while they are punched on the machine, a stop 227 is provided,
To shear the sheets from the strip 213 and punch a hole in each of these sheets, the knife 222 and the punch 224 are moved to bring them closer to and away from the base surface 212 on which the strip rests.

   In order to cut pieces of progressively increasing length and to make a hole offset from the longitudinal center of each of the sheets, the punch 224 and the stop 227 are movable with respect to the knife 222, the punch and the stop being movable in a direction parallel to the base surface, which will ventilate normally in a horizontal position, when the knife 222 moves in a vertical direction,
Relatively stationary rods 228 & 229 support punch 224. A bearing block 230 is placed in punch support 226 so that, despite the relative immobility of the punch support in a vertical direction, the latter is nevertheless movable in a horizontal direction by the bearing block 230 sliding on the guide rods 228 & 229.

   The stop 227 is supported by an arm 231, carried in turn by the rods 228 and 229 by means of a bearing 232.



   In order to move the stopper or stop 227 and the punch 224 in a direction parallel to the base surface 212, which is normally in a horizontal position, screws 233 & 234 are provided. As can be seen in FIG. 28, brackets 235 & 236 carry bearings 237 and are mounted on table 210, these brackets support screw 234 in its rotational movement by means of bearings 237.

   Blocks 238 support the rod 229. Of course, similar supports are installed to support the rod 228 and bearings similar to the bearings 237 are installed to support the screw 233 in its rotational movement,
To rotate the screw 233 of the punch and the screw 234 of the stop, a movable rack is supported by a plate 241 in its vertical movement * The rack 240 is connected to the screw 233 for its actuation by a toothed wheel 24? carried by a sleeve 243.

   Sleeve 243 is, in turn, rotatably mounted.

  <Desc / Clms Page number 19>

 -tion on a rod 244 which is an extension of the screw 233, The rod 244 supports a wheel 245 connected to the sleeve 243 by a ratchet mechanism 247, in which the pawl 247 is held by arms 248, themselves carried by a bracket 249 on the sleeve 243. A rod 250 is resiliently supported by a spring 251 against the bracket 249 of the ratchet system 247 so as to force the pawl to come into engagement with the toothed wheel 245. It is seen that the movement downward of the rack 240 will move the pawl 247 over the teeth of the wheel 245 without rotating the wheel, while the upward movement of the rack will engage the pawl with the teeth of the wheel 245 so as to rotate the wheel 244.



   To mechanically connect the screw 234 of the stopper with the screw 233 of the punch, a toothed wheel is mounted on the rod 244, in engagement with a toothed wheel 253 on an extension of the screw 233 via a pinion. crazy 254. It is understood that the wheels 252, 253, 254 can have any suitable dimension relationship; in the construction shown in the drawing, the toothed wheel 252 has twice the circumference of the pinion 854 and the toothed wheel 253, so that there is a two-to-one gear ratio, i.e. that the stopper screw 234 will turn twice as fast as the screw 233 of the punch.

   With this special ratio, the sheets can be cut to progressively increasing lengths and with the punch suitably adjusted to give the hole the offset from the center of the longitudinal axis of each sheet, the holes of each of the length sheets. progressively different will be offset by the same amount from the center of the longitudinal axis of each sheet to produce a group of sheets of the type shown in Fig. 29. 'The hole can of course be punched in any other suitable location and different sheets can also have any other desired dimensions.



   In order to function the shears 222 and the punch 224 to cut the strips of sheet metal and punch the hole, a pipe 260 is fitted, connected to a source of compressed air. The maneuver of the operator pressing the foot on a pedal 261, moves a valve 262 so as to admit the pressurized air through the pipes 263 & 264, at the top of the piston 265 which operates the shear 222. This forces the piston to move down and cut a length of the strip from the roll, Simultaneously, the air will be led through a flexible pipe connection 266, above a piston 267 which will move the punch down to punch the hole.



  In addition, air will be introduced through line 264 above piston 268, which will cause rack 840 to descend and, as already mentioned, when this or-

  <Desc / Clms Page number 20>

   -mailllère descends, the pawl 257 moves freely around the ratchet wheel 245, without turning it. When the operator takes his foot off the pedal 261, the valve 262 returns to the position shown in Fig. 30, admitting air through the pipe 270 under the piston 265 of the shear and under the piston of the rack. 268.

   Likewise, by a flexible connection 271, the air will be admitted below the piston of the punch 267, causing the latter to move upwards,
Upward movement of the rack 240 will cause the pawl 247 to engage the teeth of the ratchet wheel 245 thereby rotating the screw 233 by a determined amount depending on the displacement of the rack. Rotation of screw 233 will cause screw 234 to rotate, due to the two-to-one ratio, by twice the amount of screw 233. It is evident that the number of turns of screws 233 & 234 will determine how much the sheet metal next will be larger than the one immediately preceding it and which has just been cut out.



   In order to control the movements of the punch 224 and of the stop 227, a vernier device 272 is provided, the rotation of which causes the nut 273 to move towards or away from a stop 274 on the support 241. The distance between the nut 273 and the stop 274 represents the displacement of the rack 240.



   When the machine has been running long enough that stop 227 has moved as far as desired to have the longest sheet of the bundle shown in Fig. 29, the machine can either be returned to the starting position by turn screws 233 & 234 in the opposite direction to bring the stop 227 and the. punch 224 to the position which produces the smallest sheet of the package or the sheets can be cut by locating the positions of stop 227 and punch 224 by their displacement Towards shear 222 by a determined amount depending the rotation of the screws.

   The screws can be made to turn in the opposite direction by simply lifting the catch 247 and connecting the catch 280 with a toothed wheel 281, attached to the rod 244 but of which the downward movement of the rack can be seen easily. 240 Engage pawl 280 with wheel 281 to spin! ' screws 233 & 234.



   As the rack 240 moves down, the punch and shear also lower and, in order to prevent rotation of screws 233 & 234 as the punch and shear are lowered, a dash is mounted. -pot 282 connected to the upper part of the rack 240 and having characteristics such as to prevent the rack from descending before the punch and the shear have cut the sheet This precaution prevents the sheet from making loops,

  <Desc / Clms Page number 21>

 
With reference to schematic figures 32 to 134, a description will now be given of embodiments and variants derived from the main invention;

   these embodiments and variants are given without limitation, it being understood that all equivalent arrangements and variants must be considered as forming part of the invention,
The example which will be described with reference to Figs, 32 to 40 is more particularly aimed at the construction of cores for reactance coils where it is often desirable to have both a stop seal and a stop seal. overlap, the stop seal being provided in the column intended to receive the coil and the lap seal in the other column (s).



   Fig, 32 shows a perspective view of an induction device in accordance with this variant of the invention; 1a is a perspective view of the two packages of magnetic sheets, each forming one of the two cores of Fig. 32, and the perspective view of a ring inside which the sheets of each of the groups are assembled; Fig, 34 shows the t8les assembled in the ring of Fig.33; Fig.35 is a partial of the curved sheets whose ends come into contact by abutment; Fig * 36 is a perspective view of the assembled sheets and the mandrel employed to form the core; Fig. 37 shows the nucleus during a later stage which gives it the shape it will have in the finished apparatus;

   Fig. 38 is a side view of the core in its form when placed in an annealing furnace; Fig, 39 shows the reactance coil of Fig.32 with a core assembled with a coil around one of the columns, the other core being assembled; and Fig. 40 shows an electro-magnetic apparatus with a modified seal construction.



   Fig. 32 of the drawing shows an electromagnetic induction apparatus comprising a pre-prepared conductive coil 301, with the cores 302 and 303 passing through the hole or window of the coil, and surrounding the rectilinear parts or columns of the cores Core clamping is provided in the form of U-shaped iron bars placed on either side of the cores and clamped together by 304 bolts.



   The construction shown in Fig, 32 has two cores with straight portions passing through the hole in the coil, but it should be understood that any suitable number of cores may be employed. Each of cores 302 & 303 includes two U-shaped curved sections 308 & 307 with a stop gasket between adjacent ends 310 & 309 inside the spool window, and lap joints between the ends of straight sections 312 & 311 towards the outside,

   as can be seen in Fig. 39. Such a seal can be used for any appliance.

  <Desc / Clms Page number 22>

   -rell electro-magnetic and this particular joint construction finds its application for a reactance coil. As the two cores 302 and 303 are similar, only one of them will be described below in connection with Figs. 33 to 38.



   In order to produce the magnetic cores 302, two groups of strip sheets are prepared, these groups being generally indicated by the numerals 313 & 314 in Fig. 33. The sheets can be formed in a suitable manner by cutting pieces from a magnetic steel strip having the most favorable magnetic direction in the longitudinal direction of the strip.

   In addition, as can be seen in Fig. 33, the strips of sheets are successively cut to different lengths * Given the dimension of the cores, its position in the whole of the apparatus and the relative position of the joints, the peripheral distance of each of the elementary sheets for each layer can be determined * The sheets can be cut by hand to the dimensions thus determined, or else Be cut on a shearing machine with adjustment index, of the type already mentioned and described.



   The groups of sheets 313 & 314, shown in Fig. 33, can be assembled in the way desired to form the improved core and there is shown in Fig. 33, a clamp or clamping band in which the sheets can be assembled to form the core. The machine comprising this strip and on which the sheets are assembled has already been described with regard to the first embodiment of the process according to the invention,
In order to assemble the various sheets of groups 313 & 314 in the flange, the longest strip 316 of group 314 is inserted into the flange by bending it enough to follow the interior content of the flange surface. .

   To facilitate the assembly of the various sheets within the flange 315, pins 317 & 318, are placed in the flange 315 and extend inward. It will also be noted that the various strips of sheets constituting the group 314 each have an opening 320 located at a small distance from the end. Thus, after having introduced the sheet into the flange 315, the pin 317 is passed through the opening 320. A corresponding sheet 321 of the group 313 is then taken from this group and introduced into the flange 315 so that in the finished core sheet 316 of group 314 and the corresponding sheet of group 321 form a complete layer. Referring to Fig. 35, it will be seen that one end 322 of the sheet 316 will abut the corresponding end 323 of the sheet 321.

   However, to facilitate assembly, ends 322 & 323 of sheets 316 & 321 may be left in the overlapped position until a sufficient number is assembled. The sheets can however be made to have the ends 322 & 323 in abutment position against each other

  <Desc / Clms Page number 23>

 lengthening and bending them sufficiently when they are inserted into the ring.



   As can be seen, in particular from Figs. 34 & 35, the total length of sheets 316 & 321 constitutes a complete layer with the ends 322 & 323 butting, and the opposite ends 324 & 325 also come end to end on the opposite side of the nucleus.

   Note however that the ends 322 & 323 are not in opposition with the seal formed by the ends 324 & 325 and that, assuming the seal formed by the ends 324 & 325 located approximately in the middle of the spool column 309,310 (Fig. 39) the joint formed by the ends 322 & 323, visible in Figs. 34 & 35, will be moved slightly to the right of the centerline 326, The joint between the ends 322 & 323 can be offset of the desired quantity by simply varying the relative length of the plates 316 & 321, and, in the construction shown in Fig. 34,

   sheet 316 is longer than sheet 321 by the amount of which the joint between 322 & 323 extends to the right of axis 326.



   So that the joints in the outer leg formed by parts 311 & 312 (Fig. 39) are offset to form stop and lap joints, while the joints between parts 309 & 310 of the inner leg (Fig. 39) .39) are all in correspondence to form a rectilinear abutment joint, the next layer formed by the sheets adjacent to the sheets 316 & 321, will be formed in such a way that a sheet of group 313 will be contiguous to a sheet 316 of group 314 .

   Thus, referring to Fig. 33, a sheet 327 is taken from group 313, this sheet being the one which follows the shortest of this group 313, adjacent to sheet 321, and introduced into the ring with pin 317 passing through opening 328 and sheet 327 wrapping to the right around the inner surface of the ring (looking at Fig. 34) and adjacent to sheet 316 ... Similarly, a sheet 329 is taken from group 314 and inserted into the ring, with a pin 318 passing through opening 320 in the sheet, the latter extending to the right around the adjacent sheet 321.

   As the sheet is longer than sheet 327 by the same amount that sheet 316 exceeds sheet 321, the respective ends 330 & 331 of sheets 327 & 329 will produce in the finished core a stop seal to the left of the sheet. axis 326, as can be seen in Fig. 35.

   By thus constituting a closed magnetic core by assembling the sheets of two groups in which the sheets of one group are slightly longer than the half-periphery and the sheets of the other group corresponding to the first are slightly shorter than the half-periphery, the sheets of each group being assembled alternately, a stop-to-lap seal will be created in one of the legs. As the holes 320 & 328 are provided at the same distance from the adjacent ends of the sheets, it can be seen that

  <Desc / Clms Page number 24>

 in the opposite leg, the various ends of the sheets will be placed in correspondence so as to form a stop joint through the leg 311-312 of the finished core.



   After all the sheets have been inserted, as shown in fig. 34 and as described above, the various lap joints can be brought into the stop position by applying pressure to fingers 322 & 333 (Fig. 34) in the manner already described with regard to the first implementation process of the invention. This pressure will cause the ends of the sheets to pull away slightly) as shown in Fig. 35, after they have been forced into each other, to produce a relatively tight stop seal between the ends. adjacent sheets of each of the groups.

   Instead of stacking only one sheet at a time in each of the groups, any number of sheets can be stacked in each group at a time.



   The core can then be used in the circular shape, or it can be lengthened using an expansion mandrel as shown in Fig. 36, the system comprising two similar blocks 234 with a wedge-shaped piece (335, fig. 36). The introduction of the mandrel into the circular core represents in Fig. 36, and the insertion of the wedge 335 (Fig. 37) elongated !: the core.

   However, like the seals! are placed in opposite straight sections or legs, the use of the expansion mandrel could cause the joints to open; also, to complete the expansion operation while forcing the joints at the ends of the sheets to remain relatively tight together, the core can be placed in a press, with one leg of the core resting on a base of the core. press, the latter being provided with movable pistons 336, 337 & 338 (Fig. 37).



   By applying pressure to the four opposing parts, the core can be brought to an oblong shape as shown in Fig. 38. To maintain the core in this position, a flange is placed around the core and carries trays 339 and 340 which are securely held on either side of the core by bars 341 & 342, which can be attached to the trays by any suitable means, such as ! than spot welding ,. In order to eliminate all the harmful tensions and to fix the sheets in a permanent way in the position which they must occupy in the finished core, the whole of the core and the constructive device will be placed in a furnace to be subjected to it. annealing desired and remove any internal stress.



   The core will then be mounted around the previously constructed coil * For this purpose the consoles 339 & 340 are removed and the U-shaped portions or yokes of the core are disassembled by separating them by the application of forces acting in direction

  <Desc / Clms Page number 25>

 opposite on each of the curved parts of the core, forces which must be parallel to the longitudinal axis of the core. Rivets 343 can be placed in the holes to hold the ends of adjacent sheets relatively tight together.



  The two U-shaped parts being open are then mounted on the spool 301 prepared in advance, by inserting the ends 309 & 310 into the opening of the spool and these ends, once put back in conjunction, constitute the stop seal,
When the ends are in the stop position inside the reel window, the outer ends are pulled out, for example by grasping them by the hands, as shown schematically in Fig. 39. The sheets are then slid to their position by first releasing a sheet of part 307 of the core, then the corresponding sheets of part 308, to allow them to resume their place.

   Thus, a longer piece 344 of part 307 is dropped into place, then a corresponding shorter sheet 345 of part 308 until the ends are in the stop position, as shown in Fig. 39. The various sheets are allowed to fall back to their place until the whole of the core has taken the position of the core 303 of Fig, 39, which is shown as already mounted around the coil,
It will also be appreciated that a strip of insulating material 346 has been placed between the adjacent ends 309 and 310 of the straight part, or leg, but it should be understood that the ends can be placed in the stop position without interposition of insulating sheet, if desired, so that the ends are not subjected to harmful tensions by the use of the insulating layer 346,

   the core is provided before its annealing with a metal part 347 having the same dimensions as the sheet 346, placed between the parts 309 & 310.



   In Fig. 40, there is shown a modification of the invention comprising a coil built in advance 350, associated with two cores having rounded portions or yokes 351 & 352 which constitute a core and rounded portions 353 & 354 forming a other core. In the construction shown by this FIG.



  40, rivets 355 & 356 hold tight together the adjacent sheets of the two cores, which respectively constitute the columns entering the hole or window of the coil. The cores are in this case assembled on the pre-prepared spool, inserting the U-sections 351 & 353, and 352 & 354, in opposite directions to form the stop seal 357 and then to form in the outer straight parts, the Lap Stop Joint, in the same manner as described above in connection with Fig. 39. We will also notice

  <Desc / Clms Page number 26>

 than in construction. shown in Fig.4C, there is a recess on the two outer columns in the vicinity of the joints.



   It is well known that stop joints, unless they are carefully adjusted to the grinding wheel, are the cause of additional losses. But even in the case of an adjustment of the joint to the grinding wheel, it happens that burrs short-circuit the sheets, which further increases these losses.



   The construction variant described below, with reference to Figs. 41 to 67, allows a very precise stop joint of a special shape to be produced without having to grind the faces of the joints and thus to largely eliminate the additional losses. - additional.



   Fig. 41 of the drawing is a perspective view of an electromagnetic induction apparatus constructed in accordance with this variant of the invention; Fig. 42 is a side view of two groups of magnetic sheets used to form the cores of the apparatus of Fig. 41; Figs. 43 & 44 show steps in the improved method of joining the groups of sheets to produce the core of Fig. 41; Fig. 45 shows the sheets assembled in an annealing furnace; Fig. 46 is a sectional side elevation of one of the cores assembled around one of the rectilinear portions of the coil and the other core being assembled;

   Fig. 46a is an enlarged view of one of the parts of the seal of Fig. 46; Fig. 47 shows a device used to bend groups of sheets; Fig. 48 shows a modified method of building the core, which can be formed according to the improved method, Fig. 49 shows two groups of magnetic sheets which constitute the core of Fig. 48; Flg.50 represents another construction of a kernel constructed according to the invention; Fig. 51 shows two groups of sheets used to form the core of Fig. 50; Fig. 52 shows the two groups of sheets of Fig. 51 during their assembly before their bending in the longitudinal direction; Figs.



  53 to 56 show groups of magnetic sheets being bent and formed in accordance with a modification of the improved method; Fig. 57 shows the two portions of U-shaped cores made according to the process implemented in Figs. 53 to 56, the core being ready for annealing to remove internal stresses, Fig. 58 is a section in side elevation of a magnetic core formed from a modification of the method; Fig. 59 shows a group of sheets used to form one of the core parts of Fig. 58; Fig.60 shows the group of sheets of Fig.59 during the bending operation in the flat direction; Figs.



  61-63 show later stages in folding and shaping the group of plates of Fig. 60, and Figs. 64-67 show further modifications of

  <Desc / Clms Page number 27>

 the method of construction of the nucleus.



   Fig. 41 of the drawing represents an electro-magnetic induction device provided with a pre-prepared coil 430, with two cores: similar 431 & 432 enclosing respectively the rectilinear parts 433 & 434 of this coil 430. Each of the parts 431 & 432 comprises U-shaped portions 435 & 436 with a suitable stop seal 437 between the corresponding ends of the rectilinear parts of the U-shaped portions. In Fig. 41 there is shown a seal 437 of the type sling stop, or oblique, but it will be appreciated from the development of the description that any suitable mode of construction of the joint can be carried out in accordance with the alternative method of the invention,

   Although the two cores shown are associated with a single coil it should be understood that the method can be used to constitute any type of electromagnetic induction device, such as a transformer or a reactance coil. In addition, this process can be employed to construct electro-magnetic induction devices for a wide range of sizes and powers ranging from cores to relatively thin magnetic strips, for example of about 0.05 mm, to relative transformers. These may be used at high frequency, up to cores employing relatively thick bands, for example 0.35 mm, used in types of transformers of much larger dimensions.



   The core shown in Fig. 41 consists of two groups of plates 438 & 439 shown in Fig. 42. These sheets are preferably steel strips having the optimum magnetic direction in the longitudinal direction of the strips. The two groups 438 & 439 mount approximately the same number of elementary sheets and these sheets have a length such that the corresponding elements of each group when assembled have a total length equal to the periphery of the contour of the core along this layer. The dimensions of the core being thus given, the builder can calculate the length of each of the sheets of the two groups used to form the finished core.

   It can therefore be seen that by using various combinations of sheet lengths of the two groups, any suitable type of joint, in a sling, or with a stop, or with an overlap, can be produced.



   In order to achieve a sling stop joint as shown in Fig. 41 and represented by the number 437, one will take for one of the groups 438 sheets of the same length, The sheets of group 439, on the other hand, will have progressively increasing lengths, the shortest being at the inner periphery of the finished core , and the longest on the outside. The sheets will be cut in any suitable manner by measuring them by hand and cutting them to the desired length, or they may

  <Desc / Clms Page number 28>

 be cut on the index shearing machine described.



   This index shearing machine will produce sheets of progressively increasing lengths to form the group 439. In addition, holes 440 and 441 can be punched in each sheet at the same time as they are cut. These holes can be punched in any suitable location and in the two groups 438 and 439 the holes are punched in the middle of the length of each of the sheets.



   To assemble the two groups of sheets 438 & 439 and form the core as shown in Fig. 41, the sheets, after having been joined together in the manner shown in Fig. 42, are bent in the direction of the dish to form two portions of a U-shaped core. This folding can be accomplished in any convenient way and, when the sheets are thin enough and flexible enough, they can be folded by hand. Of course the sheets can also be folded by means of an apparatus such as will be described below with regard to Fig. 47.

   However, even if the sheets are cut as exactly as possible and the holes drilled as close to the middle of the length of the sheets as possible, when the sheets are bent to form the two U-shaped sections, the ends of the sheets may not be in the exact desired position with respect to the corresponding sheet of the adjacent part of the other portion of the core so that the corresponding sheets come into contact with each other as exactly as possible and ensure a lossy joint substantially zero.

   Accordingly, to ensure a very low loss seal when forming the relatively tight stop seal between the ends of the corresponding plates in the adjacent portions of each of the U-shaped portions of the core, suitable pressure is applied at least in a direction parallel to the sheets in the rectilinear parts of the U-shaped parts, so that the adjacent ends of corresponding sheets, which are to be fitted quite tightly against each other, are placed in equivalent planes. The application of this pressure can be carried out in any satisfactory manner and in Figs. 43 & 44 apparatus has been shown to accomplish this step.



   As can be seen by referring to Fig. 42, the group 438 is assembled such that all of the holes 440 are in line and the brach 442 then passes through all of the holes 440. pin 443 passes through all holes 441 of the plates of group 439. The two pins extend outward from the opposing surfaces of a mandrel 444, so that by applying pressure to each of the groups in In the direction of mandrel 444, all the sheets will fold together to form two U-shaped portions.

   When the tales are

  <Desc / Clms Page number 29>

 in this position, they can be placed in the machine shown in Fig. 43, which comprises two blocks 445 & 446 diametrically opposed, these blocks having openings suitably placed for the passage of the ends of the pins 442 & 443. So that the pressure is applied to the two parts of the core in a direction parallel to the plane of the sheets in the rectilinear parts of these U-shaped parts, the blocks 445 & 446 are slightly movable * Thus the block 445 can be roughly fixed and the block 446 is in connection with the end of a screw 447.

   The upper part of the screw passes through a nut 448 threaded internally at the pitch of the screw 447; the outer end of the screw 447 carries a handle 449 which can be maneuvered by the operator Parts 450 & 451 carry the nut 448 and are connected in a relatively rigid manner to the supports 452 & 453, It can therefore be seen that turning handle 449 in the desired direction, screw 447 will be driven downward and in turn will cause adjacent ends 454, 455, 466 & 457 to move closer together.



   To give the finished core a generally rectangular or oblong shape, the machine shown in Fig. 43 includes other movable blocks 458 & 459 diametrically opposed and placed in such a way that pressure can be applied in a direction perpendicular to the rectilinear parts. U-shaped parts of the core. Blocks 458 & 459 work in conjunction with screws 460 & 461, which pass through internal threads made in fixed brackets 452 & 453. By turning screws 460 & 461, the straight parts of the U-shaped portions are pushed towards the chuck 444.



   The core can, therefore, be brought to the desired shape by rotating screws 447, 460 & 461 gradually or all together by the desired amount until the core is in the position shown in Fig. 44 .



  In Figs, 43 & 44, a flange 442 of a suitable material, such as metal, already surrounds the parts of the core, the ends of this flange having openings through which the screw 447 can pass. the flange is then passed over the end of the screw and the flange is then completely wrapped around the closed core. The other end 463 of the flange then has its opening, through which the screw 447 can pass. A nut 464 is placed below the ends of the flange and, by rotating the nut so as to move the ends 462 and 463 away from the core, the flange can be tightened quite strongly around the portions of the core.

   The flange is then spot welded at both locations 465 and then cut at 466,
The core portions, with their ends in the correct abutment position, are now in the desired conditions to undergo annealing and to eliminate stresses.

  <Desc / Clms Page number 30>

 



   A weight 467 is placed on the core to hold the sheets in place until annealing is complete. After removal from the annealing furnace, the core is ready to be associated with a prebuilt coil.



   Annealing gives each of the sheets a permanent position corresponding to the relative position it occupies in the furnace, so that the sheets will naturally tend to maintain themselves in the position they occupied in the furnace4 However, to be certain that the tales will not move during the removal of the support flange 462, the pins 442 & 443 can be, during this removal, replaced respectively by rivets 470 & 471. Any other convenient means of fixing the sheets in their desired position, can be used. The band 462 can then be removed and the U-shaped portions of the core can be disassembled as shown in Fig. 46.

   These parts of the core can then be introduced with their corresponding straight U-shaped parts and tightened in the stop position, one of the parts entering the opening of the coil. A band 472 will be placed around the U-shaped portion and tightened quite strongly, then fixed by any suitable means, such as spot welding of the two ends as indicated at 473 (Fig. 46).

   As the adjacent ends 454, 455 & 456, 457 have been prepared to fit over each other quite tightly and form a low loss joint, following the method described, as long as the sheets do not come together. will not be moved, the core portions can be disassembled and reassembled around the prepared coil, as shown in Fig. 46. and the corresponding plates of each of the portions of the U-core will fit with a fairly tight stopper seal in the same position they occupied when the core was removed from the annealing furnace.



   In the oblique joint as shown in Fig. 46, the sheets all have the same thickness. It follows that the entire edge of the end of each sheet will not be in the same plane as has been shown for the sake of simplification in Fig. 46, but the joint will actually have a tiered arrangement as shown more exactly in Fig. 46a.

   the ends could, however, if desired, be brought by molding approximately in the same plane * It has already been mentioned above, in connection with Flg. 42, that, when the bundles of sheets are assembled, these bundles can be folded flat in any suitable manner, and in Fig. 47 there is shown an apparatus for performing this folding operation. The apparatus comprises two moving parts 480 & 481, U-shaped. The internal surfaces of the U-parts 480 & 481 are dimensioned to produce the desired core shape.

   The maneuvering cylinders 482 &

  <Desc / Clms Page number 31>

 
483 are designed to push the shaped parts 480 & 481 against the mandrel 444,
This maneuver will force the bundles of sheets 438 & 439 to bend together in the direction of the flat and to take the shape of a U. The parts of the core can be placed in the maohine shown in Fig, 43 described above; or the ends of the sheets may be forced together as they are placed in the press of Fig. 47 and then properly secured in the desired position until annealed.



   Fig. 48 shows two core portions 486 and 486 with stop joints 487 and 488 between the adjacent ends of the corresponding rectilinear portions of the two U-shaped portions. The core portions 485 & 486 are obtained by the folding in the direction of the flat of two bundles of sheets as described above with regard to Figs. 41 to 46.

   The two bundles which form the core parts of Fig. 48 are shown in Fig, 49 and are marked respectively at 489 & 490,
To achieve the particular shape of the joint, it is necessary that each of the two groups 489 & 490 be formed of sheets having progressively increasing lengths, the smallest sheets of each group constituting the inner layer of the finished core and the longer sheets. long constituting the outer layer.



   The sheets also have holes 491 & 492 on their longitudinal axis to facilitate stacking and to receive rivets 493. The sheets can also, if desired, have holes 494 & 495 in the vicinity of their ends. The holes in each of the t8les are drilled at the same distance from the ends thereof so that when the packages are folded into a U-shape the holes are generally aligned so that rivets 496 can be introduced into these holes. These rivets can be placed at any time during the formation of the cores, for example after leaving the annealing oven.

   Instead of rivets any other means can be employed to fasten the sheets together, for example a weld line as shown at 507 in Fig. 64.



   Fig. 50 shows a core construction having stop-lap joints. The core comprises two U-shaped portions 497 & 498 in which the ends of a number of layers in each of the portions are offset, Thus a layer 499 of the part 497 of the core extends beyond the ends of the adjacent layers 500. Similarly, a layer 501 of the next straight part of the core portion 498 extends beyond a layer 502 of part 498 of the core.

   So that the protruding layers are sufficiently rigid and take the desired position in relation to the

  <Desc / Clms Page number 32>

 to the adjacent layers when the core is reassembled around the coils, any suitable number of sheets can be employed to form each of these layers and, in particular, using strips of 0.35 or so, two to six sheets to be formed. are a suitable number
To form the core portions 497 & 498, two bundles of sheets may be cut by any suitable method and with relative lengths desired to achieve the construction of the lap joint. This lap joint being of the general type. in a sling in Fig. 50,

   the two groups 503 & 504 consist of sheets having progressively increasing lengths and the sheets of groups 503 & 504 are, during their cutting, provided with holes 505 & 506 respectively, offset by the same amount with respect to the longitudinal center of the sheets * The sheets will be cut by any appropriate means, in particular by means of the Index cutting machine, already mentioned above and already rewritten These sheets will then be assembled longitudinally by turning the sheets of the various layers upside down and the idea The general practice of assembling magnetic sheets in this manner to produce a stop-and-lap joint already described will be applied.



   The pillowcases of groups 503 & 504 are assembled on pins 442 & 443 of Mandrel 444. Note that the different packages are assembled with adjacent layers extending in opposite directions. Thus, first layer 499 has its longest side extending to the left of pin 46 with respect to hole 505, while adjacent layer 500 has its longer side projecting to the right of the pin. The sheets four to six in number at a time can be assembled in this way to form a large number of layers, the ends of which are overlapped.

   The sheets can then be curved in the direction of the flat and then assembled in the apparatus shown in Figs. 43 & 44, so as to abut in a fairly tight manner the corresponding layers of the adjacent rectilinear parts of the U-shaped portions.



   The cores will be assembled, folded in the direction of the flat, and then pressure will be applied to the ends of the sheets forming the two straight parts of U-shaped portions. In Figs. 53 to 56, another method is shown for bending a bundle of sheets and applying pressure. The group of plates 439 of Fig. 53 is assembled by a pin 510 passing through the openings 441.



  The pin 510 extends from the shaping piston 511 and the stack 439 of the sheets is carried by the upper surfaces of two vertical side pieces 512 & 513 of the bending mandrel. By pushing the piston 511 down, in the direction

  <Desc / Clms Page number 33>

 of the arrow, the group 439 will be folded flat, forming a U-shaped core part as shown in Fig. 54. The piston 511 or die has surfaces 614 corresponding to the inclination of the sling stop seal 437 of the construction shown in Fig. 41. By exerting pressure on the ends of the sheets via the inclined surface 514, these ends or their corresponding edges will therefore be placed in the same plane.

   In order to properly support the sheets, the parts 512 & 513 are movable in a direction at right angles to the movement of the piston 511. These parts will be actuated by any suitable means, for example by means of their respective connection with screws. 515 & 516.



  Pressure can be applied by piston 511 and walls 512 & 513, but simultaneously or gradually in the direction of the core, so as to achieve the desired stop seal. In order to maintain the various sheets in the desired position, after this position has been reached under the effect of the pressure of the piston 511 and the parts 512 & 513, tabs 517 & 518 are provided between the adjacent surfaces of the portion of the core and blocks 512 & 513.

   Note that these tabs) 517 & 518 must be placed in the bending mandrel before the sheet metal pack 439 is pressure inserted into it * Link bars 519 can be placed between the tabs 517 & 518 and y be welded in such a way as to hold the sheets securely in position, as shown in Fig. 54. Similar bars 619 will be placed on opposite sides.



   In order to produce the U-shaped portion of the core which can fit over that shown in Fig. 54 and make the complete magnetic core, a group of sheets 438 is formed in the same way, as shown in Figs. 55 & 56 Since a sling stop-seal is obtained when the group of plates 438 is U-shaped with the straight portions, or legs, extending upwardly, a piston 520 is provided with surfaces. inclined 521 which are in a plane different from that of the surfaces 514 of the previous pistons / The surfaces 521 are however placed with respect to the surfaces 514 in such a way that if the U-shaped core portion shown in Fig. 56 was upturned, the edges of the sheets,

   produced by the surfaces 521 would abut quite firmly against the edges of the sheets produced by the surfaces 514.



   After making this second half of the core shown in Figs. 55 & 56, the halves 522 & 523 can be assembled as shown in Fig. 57, then placed in an annealing furnace to remove internal stresses, when the parts of the core 522 & 523 are assembled as shown

  <Desc / Clms Page number 34>

 Fig. 57 With the ridges 524 & 525 in the stop position, the corresponding sheets of the two straight parts of each of the core halves will be brought into even closer contact during the annealing operation. After annealing, parts 522 523 can be removed and fitted around the deep coil, as described in connection with Fig. 46.



   It should be understood, however, that instead of fitting the parts 522 & 523 to one another before placing them in the annealing furnace, these parts 522, 523 could be separately stacked, placed in the annealing furnace. and then removed and mounted on the spool.



   Any other type of seal can be formed according to the method described in connection with Figs. 53 to 56, and in Fig. 65 there is shown a piston 526 constructed to form the stopper seal on a core portion 527. , this joint being located in an Elan approximately perpendicular to the plane of the sheets in the rectilinear part of the core.



   In Figs 66 & 67 there is shown a modified method for aligning the ends of a core half, this method comprises providing openings 528 in a group of sheets 529, these openings being placed in such a way that after bending the group of sheets to form a U-core, the holes 528 are roughly in line, The sheets can then be arranged in a suitable way in case they do not have their holes aligned so that one can pass a rivet through these holes after matching them.

   This procedure will give a joint construction where the edges are placed approximately in the same plane, although these edges might not be as exactly in line as in the construction obtained by the method which involves the appli- cation. cation of a pressure on the sheets as described above in connection with Figs. 41 to 47 or 53 to 56.



   Figs. 58 to 63 show a core construction and a method for its realization in the case where the sheet bundles are relatively long and flexi. wheat. Thus fig. 58 shows a core comprising parts 530 & 531 each of which is made in the shape of a U. Each of the parts 530, 531 is obtained by bending a group of sheets of progressively increasing lengths, as shown in Fig. 59. Group 532 is assembled by placing my ends of one of the sides 533 in alignment. This can be achieved by making holes 534 near both ends of the sheets, each of the holes 534 in each sheet being the same distance from the end of the sheet.

   A 535 pin will be passed through the holes and a

  <Desc / Clms Page number 35>

 Clamp 536 will be placed on opposite faces of the group. The sheets will then be bent, a second flange 537 clamping the opposite faces to the other end 538 of the group, as indicated by the mixed line of Fig.60. The group of t8les 532 can be given any desired shape, as shown in Figs. 59 to 63.



  In this way, the central parts of the t8les are kept relatively straight by movable locking pieces 539 and the ends are plunged by means of movable pistons 540 to form straight portions which extend at right angles. The core can then be held in this position by the clamping plates 539 and by a bracket comprising plates 541 and connecting rods -AU * The core will then be annealed in this state and, after annealing, it can be mounted. on a preformed coil, the two core portions shown in Fig. 63 can be placed one above the other in the furnace and annealed in this position. The core construction, shown in Figs. 58-63, will be employed with advantage where the t8les are relatively long and flexible.



   In the foregoing description, it has already been mentioned that the two U-shaped parts of a core provided with a lap joint in the straight part intended to receive the coil must be adjusted with care. However, if the layers or bundles of interpenetrating t8les are not thick enough, some difficulty may be encountered when pushing the two U-shaped halves of the core into each other and it may happen that the ends which protrude do not immediately fit in the desired locations between the adjacent ends of the layers of the other U-piece.

   This happens in particular when several fairly thin sheets are used and when it is desired to have a stop-and-lap joint in the straight part of the core poraant the coil. When the two U-shaped parts of the core are pushed into each other in a direction approximately parallel to the plane of the sheets of the straight part of the core, the ends may buckle or collapse instead of squeezing. interpenetrate to form the stop and lap joint.



   The variant below, to which Figs. 68 to 81 has as its object a construction which makes it possible to overcome these drawbacks. This variant makes it possible to produce inside the calonne, a stop-and-overlap joint of easy adjustment and simple and effective construction.



   Fig, 68 is a perspective view of an electromagnetic induction apparatus, for example a transformer constructed in accordance with this variant; Fig. 69 is a top view of a sheet used in one of the parts of the core

  <Desc / Clms Page number 36>

 of Fig. 68; Fig. 70 shows a stack of sheets for forming one of the U-shaped halves of the cores of Fig. 68; Fig. 71 shows another stack of sheets of Fig. 70 assembled to produce an oblique stop or sling and lap joint; Fig. 72 is a perspective view of the stack of Fig. 71, Fig. 73 is a view of the stack of sheets of Figs. 71 & 72 before this stack is bent to produce a U-core ;

   Figures 74 & 75 show the cell of Figure 73 in various stages of the production of the U-part; Fig. 76 is a perspective view of two U-shaped parts of the core prior to their assembly around the coil; Fig. 77 is a sectional side elevation of the transformer type of Flg.68 with one of the cores mounted on the coil, the other core being assembled; Fig. 78 shows a stack of sheets employed to constitute a modification of the invention; Fig. 79 shows two U-shaped core parts which are produced by stacks of sheets of the type of Fig. 78;

   Fig. 80 is a sectional side elevation showing a further modification of the alternative construction and Fig. 81 shows this variation of the invention applied to a sling stop joint.



   Figure 68 of the drawing shows an electro-magnetic induction apparatus such as a transformer, having a coil 601, with a partial core formed of the U-shaped halves 602 & 603 which surround one side. 604 of the coil and a similar partial core formed from the halves 605 & 606, surrounding the other side 607 of the coil 601.

   Although two partial cores are provided around two sides of the coil, it should be understood that any number of partial cores can be fitted around a coil or an appropriate number of partial coils - constituting the coil. winding,
In Fig. 68, the complete core comprises the U-shaped elements 602, 603, 605 & 606, and the stop joints 608 and 609 of the type which will be described in detail hereinafter are respectively provided between the core elements 602-603 and 605-606.,
To make up the core parts shown in Fig. 68, a number of plates 610 are taken, one of which is shown in Fig. 69.

   These sheets will preferably be made of a steel having a clearly characterized rolling direction and the most favorable direction for the magnetic flux of which is the longitudinal direction of the strips. As a bundle of sheets of the type shown in Fig. 69 is bent in a U-shape to form a core half, it is easy to understand that the layer to form the outer perimeter of the core of-

  <Desc / Clms Page number 37>

 -will be longer than the layer adjacent to the inner perimeter, the difference in length being proportional to the thickness of the core.

   This is why, in order to achieve joints located in a plane perpendicular to the plane of the sheets in the straight parts of the U-shaped core, rather than to form an oblique or sling joint, the sheets have a progressively increasing length, it is that is, the longer sheet will be at the outer periphery and the shorter at the inner periphery. A package of sheets thus prepared is shown in Fig. 70 and generally indicated by the number 611. The longest sheet 610 is at the top of the pile and the shortest sheet 612 is at the bottom and the builder in possession of the dimensions of the finished core, can calculate the lengths of each of the sheets to make the U-shaped part of the core.



   When two U-core halves are associated with a conductor winding and a lap joint is desired, care must be taken during assembly to ensure that the adjacent ends of the sheets of the two halves U-shaped come to their desired position, In order to achieve a joint which facilitates the assembly of the two U-shaped halves of the core with joints in the straight parts, the ends of the tales are cut diagonally with respect to the longitudinal axis of these sheets, and the latter are further displaced at the periphery in order to produce abutment and overlapping joints so that, when the ends of the two U-shaped parts of the core are brought together, the ridges extending at an acute angle meet the first ,

   The Applicant Company has observed that this practice considerably facilitates the assembly of the elements of the core. Referring to Fig. 69, it will be appreciated that the sheet 610 has ridges 613 & 614 which are placed diagonally with respect to the longitudinal axis as well as with respect to the direction of the most favorable magnetic path in the sheet.



  The other sheets of the stack shown in Fig. 70, also have edges whose planes are parallel to the planes of edges 613 & 614, the difference between the various sheets being that they have lengths gradually increasing. These tales can be produced by any suitable method, such as cutting a strip by hand, or on a shearing machine of the type described above.



   In order to shift the adjacent edges of the contiguous layers which constitute the U-shaped pieces of the core, the different layers of sheets are displaced longitudinally, as can be seen in Figs. 71 & 72. To facilitate this longitudinal displacement, the sheet 610 of Fig. 69 bears holes 615 & 616 towards its

  <Desc / Clms Page number 38>

 In addition, the holes 615 & 616 are placed at different distances from the neighboring edges, the hole 615 being relatively close to the edge 613 while the hole 616 is further away from the edge 614 and it will be seen, during of the description,

   that the difference between the distances of the holes 615 & 616 of the neighboring edges determines the value of the overlap of the contiguous joints in the finished core.



  In addition, the other sheets of package 611 are also provided with holes similar to holes 615 & 616, these holes being spaced from the edges of the sheets by an amount equal to the distances from the edges 613 & 614 of holes 615 & 616 in the sheet 610.



   To offset the joints as well, the various sheets or groups of sheets in package 611 are assembled by reversing the adjacent sheets, as shown in Figs. 71 & 72. Thus sheet 610 will be assembled with its hole at one end of the package, for example to the left of the package shown in Figs. 71 & 72, while the next sheet will be assembled with its hole 616 placed on the right side of the package shown in Figs. 72 & 73. This emerges more clearly from Fig. 73 where the sheet 610 has the neighboring hole 616 on the left side. of the package, while the next sheet 617 is provided with a hole 615 opposite the hole 616. In this way, the sheets 610 and 617 are moved on the periphery and an edge 613 of the sheet 610 protrudes an edge 618 of the sheet 617.



   The arrangements of the bundles of sheets shown in Figs. 71 & 72 are shown for the purpose of making the description clearer, it being understood that, in the realization of the core elements, the sheets can be taken on a stack as shown in Fig. 70 and re-stacked directly as shown in Fig. 73. any number of sheets may be used to make up layers 610 & 617, this number depending on the thickness of the sheets and, with sheets 0.25mm thick, three such sheets per layer will give a suitable thickness .



   Oven to facilitate stacking, the sheets can be stacked by placing a pin 619 through the corresponding holes. A mixed line 620 has been drawn to the opposite ends of the sheets, showing how the holes at this end of the sheets line up when the latter are stacked as shown in Fig. 73.



   In order to facilitate the bending of the U-shaped sheets, the ends of the adjoining sheets will be placed between the mandrels 621 & 622, as shown in Fig. 73 with these mandrels 621 & 622 being tightly locked on the opposite sides of the stack.



  Mandrel 621 is rotatable about axis 623 and the sheets are pressed and forced against fixed stop pin 624. One rotating the mandrel approximately

  <Desc / Clms Page number 39>

 
90, as shown in Fig. 81, the sheets will be bent enough so that a spindle
625 can pass through the holes of the free ends of the sheets, the latter are then bent more completely until the pin 625 can pass through the corresponding holes of the mandrels 621 & 622 and, at this time, the pin 619 can be removed. A third mandrel 626 is then secured against the free surface of the sheet bundle so that the assembly is held relatively tight as
Shown in Fig. 75.



   To eliminate the harmful tensions resulting from the bending of the sheets and to give them a permanent fixation in the position of Fig. 75, the assembly with the three mandrels is placed in a furnace to be annealed, or else two Corresponding parts of a core can be assembled and then annealed in the furnace in this state.



   After removing the sheets from the annealing furnace, rivets 627 will be introduced into the holes in the facing sheets, so as to hold these sheets fairly rigidly in the position they had at the exit from the heating furnace. annealing,
The assembly of the U-shaped parts of the core with the coil 601 is done by threading through the window as shown in Fig. 77.

   Thus the U-shaped parts of the core 602 & 603, were assembled around the straight parts 604 of the coil
601, while the U-halves 605 & 606 of the core are, in this process, assembled around the part 607 of the coil,
The Applicant Company has discovered that when the halves of a core of the type shown in Fig. 77 are mounted on a preformed coil and the edges of the contiguous sheets of the two halves of the core are arranged angularly with respect to one another. 'other in the direction parallel to the plane of the sheets in the straight parts, the protruding corners 628 & 629 (Fig. 78) are the first to come into contact, as can be seen from the examination of Fig, 78,

  and that it is much easier to assemble the U-halves with this arrangement, to make a lap joint, when edges protruding diagonally are the first to meet.



   In the cores described above, the contiguous sheets are offset longitudinally so that the corresponding ends of contiguous sheets of each U-shaped part are spaced apart from each other. It will be noted, however, that the corresponding edges of the contiguous sheets can be placed relative to each other in any suitable manner and, in Fig. 78, there is shown a stack in which the sheets are stacked such that the contiguous edges of the bundles of sheets cross each other in the vicinity of the middle of each bundle * The stack of sheets

  <Desc / Clms Page number 40>

 shown in Fig. 78, is formed of elementary sheets similar to those shown in Fig. 70,

   except that the holes are located at the same distance from the neighboring edges, instead of being at different distances as was the case with Figs. 69 & 70 * So package 630 is similar to contiguous package 631 , except that ltun is returned from 180. Layer 631 is also slightly longer than layer 630, in order to form joints which, in general, extend from the interior surface of the final core to the exterior surface of the latter, in the same plane. generated Packages 630 & 631 may include any suitable number of sheets.



   The stack of sheet metal bundles of Fig. 78 can be folded into mandrels in the same manner as already described above with respect to Figs. 73, 74 & 75, so as to form part 632 of the core shown in Fig. Fig. 79. This Fig. 72 also shows a part 633 of the core similar to 632. After having been bent to assume the shape which they should have in the finished apparatus, the cores should be annealed and, after the stress has been removed by annealing, can be mounted on a coil. Cores can also be assembled, annealed, then disassembled and reassembled around a coil.



   In Fig. 80, the core parts 602 and 603 are shown with the difference that the guide pieces 634 are placed against the inner and outer surfaces of each of the straight parts of the core half 602. These guides 634 can be made of any suitable material, for example steel, and fixed by rivets 627. It is evident that, during assembly of parts 602 & 603 around the straight part of the spool, guides 634 will facilitate assembly so that the corresponding ends of the two halves of the core move to the desired relative positions, as shown in Fig. 80.



   Fig, 81 shows a construction having the same type of joints as that of Fig. 79, except that the joint is made in an oblique direction crossing from the inner layer to the outer layer, instead of being made. in planar joints, This type of oblique and stepped joints is obtained by giving the bundles of sheets suitable lengths and, for a type of sling joint, one group of sheets may have progressively increasing lengths and the other group, the same length. The core of the type shown in Fig. 80 may be made and assembled as described above and referring to Figs. 68 to 77.



   Stopper and lap gaskets can be combined in various sizes. The variant described below (Figs. 82 to 101) relates to such a combination of abutment and overlap joints between the same elements of a layer and in the

  <Desc / Clms Page number 41>

 various sheet layers of a core, for induction devices, this core being produced according to the general principle of the invention.



   Fig. 82 of the drawing is a perspective view of an electro-magnetic induction apparatus made in accordance with this variant of the invention; Fig, 83 shows two packets of sheets used to constitute the cores of Fig, 82; Figs. 84 and 85 show steps in folding the sheets of the packages of Fig. 83; Fig. 86 shows the groups of sheets after their assembly in accordance with the general prooedes of the invention; Fig. 87 is a perspective view of the core of Fig. 86 and showing an expanding mandrel; Figs, 88 & 89 describe the steps in the transformation of a core of the approximate shape of a torus, into a rectangular core;

   Fig. 80 shows the apparatus of the with a partial core mounted around the coil, the other partial core being assembled: Fig. 91 shows another method of assembling the sheets around the straight part of the coil; Fig. 92 shows a modified core construction; Fig.93 shows in perspective two packages of t8les employed in the core of Fig.92; Fig. 94 shows one of the sheets of the package of Fig. 93 after the folding operation: Fig. 95 shows a core assembled with a group of sheets of Fig. 93; Fig. 96 schematically shows a number of cores of the type of Fig. 92 brought together in a furnace to undergo an annealing treatment;

   * Fig. 97 shows cores of the type of Fig. 92 assembled around the straight parts of a coil; Figs. 98 & 99 center modifications in the construction of the core shown in Fig, 92; Fig. 100 shows two bundles of sheets used for forming the core of Fig. 99 and Fig. 101 shows a modified method of assembling with a coil of the cores of the type shown in Figs, 92 to 99.



   The Induction apparatus of Fig. 82 has a form-built coil 701 and two similar partial cores 702 & 703, respectively surrounding the straight portions 704 & 708 of the coil. Each partial core of the portions 702 & 703 includes two U-shaped halves 706 & 707 with a lap stop gasket 708 between the corresponding ends of the straight halves of the U-shaped portions.



  In Fig. 701, there is shown a seal 708 of the type referred to as Sling stop and overlap seal, but it will be easy to understand from the following description that any other suitable type of seal can be made. in accordance with the invention. Although two core elements surrounding the winding are shown, it should be understood that any suitable number of core elements can be combined with an appropriate number of coil elements to form any electromagnetic device. induction, such as a transformer or coil

  <Desc / Clms Page number 42>

 reactance.

     In addition, this variant makes it possible to produce electromagnetic induction devices of all sizes and for all kinds of applications, as well as cores composed of relatively thin magnetic sheets for high frequency applications, the cores composed relatively thick strips applying to relatively large-sized types of transformers.



   To make the core shown in Fig. 82, two sets of sheets are used, as shown in Fig. 83. These sheets will preferably be made of steel with a high magnetic directional effect, the most favorable magnetic direction being in the longitudinal direction of the strip (, The two packages 709 & 710 have approximately the same number of elementary sheets, these sheets have lengths such that the corresponding elements of each of the groups have, in the partion layer under consideration, approximately a total length equal to the length of the periphery of the finished core in that layer.

   They may, however, have any other suitable length. The dimensions of the finished core being thus fixed, the manufacturer can calculate the length of each of the sheets of the two packages which will be used to constitute the finished core. It will also be noted that various combinations of the lengths of the sheets of the two packages allow any desired type of joint to be made, in a sling with a stop or overlap, as will be explained more clearly below *
The making of the sling joint with overlap and stop. as shown in Fig. 82 and represented by the numeral 708, requires that in one of the groups 709 all the sheets have approximately the same length.

   The sheets of the other group 710, on the other hand, will have progressively increasing lengths, the shorter length being both employed for the inner periphery of the core and the corresponding strip of the greater length being employed for the outer periphery.



  These sheets can be cut to the desired dimensions by any suitable means, but will preferably be cut by means of the machine already described and sheets thus cut to progressively increasing lengths make it possible to constitute the group 710. Openings or holes 711 & 712 will be punched in each of the sheets by the same machine, during cutting. These holes can be punched at any convenient place in the sheets and in both groups 709 & 710 the holes are punched with a certain offset from the center of the longitudinal axis of each sheet, as shown in Fig. 83 . Holes 711 & 712 can be omitted if desired, but $ it serves to facilitate assembly.



   To assemble the sheets of groups 709 & 710, an elementary sheet, for example

  <Desc / Clms Page number 43>

 example that marked 713 of group 709 can be passed between a number of cylinders 714 set to give the t8le any desired shape, preferably an approximately semicircular shape, as shown in Fig. 85. Each sheet of the group will be bent in a similar way and joined with the others as shown in Fig. 86. In order for the assembled sheets to form a closed core, a sheet 713 of group 709 and a sheet 716 of group 710 are placed with their ends abutting against each other.

   Likewise, a next sheet 716 of group 709 is placed against sheet 713, while the next sheet 717 of group 710 is placed against sheet 715, the ends of sheets 716 and 717 abutting against each other. . This assembly can be carried out by taking one sheet after another in the manner described, or a certain number of sheets, three or four for example, can be assembled together to form layers each comprising a certain number of sheets. sheets of the same group.



   The offset of the stop joints will be obtained by assembling the sheets with a longitudinal displacement such that the joint 718 between the sheets 713 and 715 is not in alignment with the joint 719 between the sheets 716 and 717. This displacement can be carried out by any suitable process and, in the construction shown in the drawing, it is carried out by overturning the adjacent sheets of the group longitudinally. Since holes 711 and 712 are placed out of center, when sheet 713 is placed by passing a pin 720 through hole 711, the longer side of this sheet will be either to the right or to the left of the pin and , in the construction shown in Fig. 86, we see that this long read part is to the right of pin 720.

   Likewise, the sheet 715 is assembled by passing a pin 721 through the hole 712 and with its smaller side to the right and its larger side to the left of the pin 721. Then assembling the sheet 716, the pin 720 passed through hole 711 with the longer side in the direction opposite to sheet 713, therefore to the left, while sheet 717 is placed with pin 721 passing through hole 712 with the short side of this sheet 717 towards the left of pin 721. By assembling the sheets in this way, the joints of the adjoining layers are offset. As the sheets before assembly have already received a permanent semi-circular configuration, the sheets will maintain themselves. without having to place them in a mandrel or ring.

   This practice therefore facilitates the assembly of the sheets and they can be superimposed from the inside to the outside to form a torus-shaped construction, as shown in Fig. 86. In other words, the sheets constituting the inner layer are placed first and

  <Desc / Clms Page number 44>

 the layers are superimposed progressively towards the outer periphery of the core.



   In order to give the sheets the shape they should have in the finished core, the core of Fig. 88 can, after assembly, be lengthened in any suitable way, and in Fig. 87 there is shown a mandrel d expansion 722 specific to this operation.

   The sheets will be held in position during this expansion by flanges 723 placed around the outer periphery, these flanges being spot welded at 724. When the corner piece 725 of the expansion mandrel 722 is pressed into the mandrel, the core will be forced. to take a substantially rectangular shape ,, However, the use of such a simplified expansion mandrel could break or separate the seals at 718 and 719 as well as the other seals and it is necessary to apply pressure on them. outer surfaces of the core, as shown in Fig, 88. For this purpose the core will be placed on a suitable seat and a piston 726 will be pushed down to make the core more closely match the shape of the mandrel.

   Movable pistons 727 & 728 will be arranged to exert pressure in a plane at right angles to the pressure exerted by the movable pisten 726. When the core has taken the desired shape, it will be held in this position by a support. including the plates 729 and 730 and the connecting plates 731 and 732.

   As can be seen in Fig. 88, the spacers 731 and 732 can be attached to the plate 729 and when the core has reached the desired shape the ends of 731 & 732 will be attached to the plate 730, for example at by spot welding * After the core has reached the desired shape and has been held together by plate 729 &. 730, we will submit it. he. suitable annealing to eliminate internal stresses and to give the various sheets their permanent position.



   After removing the core from the annealing furnace, it is in the conditions required to be assembled with any suitable type of coil. As shown in Fig. 90, the elements 706 & 707 of the core are disassembled, then assembled again around one of the rectilinear parts 704 of the winding. To the right of Fig. 90, there is shown a partial core after its assembly around the coil, and the other partial core during assembly. In order to maintain the various sheets in the desired position, rivets 732 are placed in the holes 710 & 711 and serve to facilitate the assembly of the sheets.



   The joints can be made in any suitable place on the periphery of the core and, when these joints are placed in the rectilinear parts, as shown in the construction shown in Figs. 82 & 90, the U-shaped parts

  <Desc / Clms Page number 45>

 706 & 707 are assembled by pushing them against each other in a direction parallel to the plane of the sheets in the straight parts.

   In order to facilitate the assembly and so that the ends of the sheets are replaced in the desired position, a certain number of sheets will be taken for each layer - which makes the cantilevered ends sufficiently rigid sheets. so that they return to the required position, the Applicant Company has found that by assembling two U-shaped core parts, of the type shown in Fig. 90, and by using two or three 0 @ 25 mm sheets thickness for each layer, the sheets will return to their respective positions in the assembly, as shown in Fig. 90,

   When it is desired to use a smaller number of sheets in each layer than that which could be easily assembled by inserting the one-piece U-part 706 to fit into the U-part 707, as shown in Fig. 90 , some sheets can be introduced separately as shown in Fig. 91.

   With this method of construction, it is advisable to have the stop and lap joints as close as possible to the end of the opening or window of the coil, in order to facilitate the assembly of the insulated sheets,
In Fig. 92, another method of building a core has been shown with the joints in the curved parts, rather than in the straight parts, the sheets can however be assembled in one or the other way already described. .



  The core of Fig. 92 comprises two U-shaped parts 733- & 734, with the joints in the curved parts 735 & 736, The part 733 of the U-shaped core is formed from a group of plates 737, shown in Fig. 93, while the part 734 is formed from a group of similar sheets 738 of the same Fig, 93, These sheets will be assembled in any suitable manner, for example giving them a permanent semi-circular shape, as illustrated in Fig94 where we see an elementary sheet 739 of group 737.

   Sheet 739 will be assembled with a corresponding sheet 740 of group 738, so that these sheets 739 & 740 constitute a layer in the finished core (Fig, 95) ,,
Likewise, the following sheet 741 of group 737 will be assembled against sheet 739 with a sheet 742 of group 738 against sheet 740. The assembly of the sheets will be facilitated by the holes 743 drilled in the sheets of group 739, these holes being placed at the same distance from the corresponding sheet ends. The holes will be drilled by any process such as, for example, at the same time as the t8les are cut on the shearing machine already described. Likewise, holes 746 will be drilled in the group of plates 738.

   When the sheets are assembled as shown in Fig. 95, pins 745 & 746 will be passed through the holes to hold the sheets

  <Desc / Clms Page number 46>

 in position, the plates of the opposite ends shown in Fig. 95, can be held in a suitable manner, for example by a magnetic fastening device 747. A small plate 748, temporarily spot welded to the plates 739 & 740 and indicated by the number 749, will maintain the interior t8les 739 & 740.



  Holes 743 '& 744' can also be made at the other ends of the sheets to receive pins, in which case the magnetic fastener is no longer necessary.



   To achieve the construction of the particular joint of Figs. 92 & 95, the corresponding sheets of each of the bundles 737 & 738 of Fig. 93 are cut such that the total length of the corresponding sheets of each bundle forms a complete curve, is slightly larger than the periphery of this layer. It follows that the adjacent ends 750 & 751 of the respective sheets 739 & 740 are placed in the stop position, while the opposite ends 752 & 753 are in the overlapping position.

   In order to produce a diversion in the joints the neighboring layer, which is constituted by the plates 741 & 742, will be assembled so that the ends 754 & 755 adjacent to the lap ends 752 & 753 are placed in the stop position, while that the opposite ends 756 & 757 are placed in the overlapped position. With such a joint construction, the adjacent ends of the sheets of each of the layers are in the abutment position, while the other adjacent ends will be in the overlapping position.



   After the sheets have been assembled starting with the inner layers and working up to the outer layer, to form a torus-shaped core as shown in Fig. 95, the core can be annealed in This is if the finished core is to be circular, or it can be elongated to form a rectangular core as described in connection with Figs. 87, 88 & 89.



  * As in each of the curved parts the joints of each layer are alternately in the overlapped position, these joints are in fact self-locking, so that an expansion mandrel 722 can be used to produce a rectangular shaped core without having to fear that the joints will come loose, as they could in the construction mode shown in Fig. 82.



  The cores can then be annealed to remove stress, by stacking these cores in a furnace, as shown schematically in Fig. 96. A suitable weight 758 will be placed on the core stack so that the straight portions for receiving the windings are quite strongly compressed. The Induction device will thus have a high space factor *
To mount the preformed coils on the cores, after the latter

  <Desc / Clms Page number 47>

 were annealed and removed from the furnace, disassembled to form two U-shaped parts 759 & 760, as shown in Fig. 97.

   The core 759 will then be passed through the opening or window of the coil 762 and reassembled with the U-shaped part 760 by pressing the ends into contact in a direction parallel to the planes of the sheets.



   In the construction shown in Fig. 97, the two core parts are placed around the straight parts 763 & 764 of a coil and, after one of the partial cores has been assembled around the straight part 764, the second core part will be mounted around part 763. Since the opening is already half-filled and if this opening has been designed in such a way that the finished core almost completely fills it, this particular method of construction of the Fig. 97 requires that the curved part of the U be slightly bent in order to pass through the space between the outer periphery of the core 759 and the inner surface of the reotilinear part of the coil, Accordingly and in order to facilitate assembly of the U-shaped parts 765, we will first assemble the sheets of part 765,

   without giving them almost any flexion. The remaining half of the sheets for the completion of the U-shaped portion 765, can then be assembled by slightly bending one end as it is passed through the remaining space. A sheet 766 will be slid through the opening as shown in Fig. 97, and one end 767 will be slightly curved in order to allow it to pass through the relatively confined space. a slight bending and, as a relatively small part of the total core is to Bend, it will be understood that only a very small amount of harmful stresses can occur in the whole of the finished core,

   
The Applicant Company has found that a joint construction of the type shown in Figs. 92 to 97 gives a very efficient high efficiency core and in the table below the losses in the core have been plotted in watts per kg. , as a function of the magnetizing current in ampere-turns per cm, for a transformer constructed with gaskets according to the process of Figs. 92 to 97 above:
 EMI47.1
 
 <tb> Density <SEP> in <SEP> kilo-lines <SEP> Current <SEP> of excitement <SEP>: <SEP> Loss <SEP> to <SEP> kernel
 <tb> by <SEP> cm <SEP> square <SEP>:

    <SEP> (amp. <SEP> tours <SEP> by <SEP> cm) <SEP> (watts <SEP> by <SEP> Kg)
 <tb>
 <tb>
 <tb> 13,500 <SEP> 0.394 <SEP> 1.24
 <tb> 14,300 <SEP> 0.476 <SEP> 1.4
 <tb> 15,000 <SEP> 0.67 <SEP> 1.63
 <tb> 15,800 <SEP> 0.95 <SEP> 1.84
 <tb> 16,700 <SEP> 1.415 <SEP> 2.15
 <tb> 17,500 <SEP> 2.36 <SEP> 2.44
 <tb> 18,000 <SEP> 2.85 <SEP> 2.56
 <tb>
 <tb>
 

  <Desc / Clms Page number 48>

 
The above figures were taken from a transformer (3 KVA, 120 volts, 72 turns, with an iron weight of 16 Kg and an average length of the magnetic flux path of 50.8 cm.



   Fig. 98 shows an induction device with a core comprising a stop-lap joint of the type shown in Figs. 92 and 97, except that the joints are placed in continuation with the opposite faces of the coil, so that the Partial cores of roughly L-shape can be assembled without having to bend any of the sheets.



   This core comprises the elements 768 & 769 surrounding a rectilinear part 770 of the coil. One of the seals 771 is in line with the inner surface of the straight portion 770 of the spool, while another seal 772 is in line with the outer surface of the straight portion 770 ,, Similar portions 768 'and 769' surround the other rectilinear part 770 'of the reel from opposite sides.

   The core parts 769 and 769 'can therefore be mounted respectively with the parts 768 and 768', assembling a small number of layers at a time. It should be understood that in the construction according to Fig. 98, a gasket is provided similar to that shown in Fig. 92, i.e. in each of the layers the ends which touch the gasket 771 are in the abutment position, while those which touch each other opposite to seal 772 are in the overlapping position.



   The Applicant Company has found that a type of seal in accordance with Fig. 98 leads to a type of core with very good efficiency and, in the table below, core losses in watts per Kg have been shown as a function of excitation current in ampere-turns per cm, for a transformer of the type in Fig. 98.
 EMI48.1
 
 <tb>



  Density <SEP> in <SEP> kilo-lines: <SEP> Current <SEP> of excitement <SEP> Loss <SEP> to <SEP> kernel
 <tb>
 <tb>
 <tb> by <SEP> cm <SEP> square <SEP> (amp. <SEP> tours <SEP> by <SEP> cm) <SEP> (watts <SEP> by <SEP> Kg)
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb> 12.7 <SEP>: <SEP> 0.365 <SEP>: <SEP> 1.1
 <tb>
 <tb>
 <tb>
 <tb> 13.5 <SEP> 0.43 <SEP>: <SEP> 1.275
 <tb>
 <tb>
 <tb>
 <tb> 14.3 <SEP>: <SEP> 0.53 <SEP> 1.4
 <tb>
 <tb>
 <tb>
 <tb> 15.0 <SEP> 0.73 <SEP>: <SEP> 1.63
 <tb>
 <tb>
 <tb>
 <tb> 15.8 <SEP>: <SEP> 1.18 <SEP>: <SEP> 1.94
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb>
 <tb> 16.7 <SEP> 1.95 <SEP> 2.22
 <tb>
 The above figures were taken from a transformer of 1.5 KVA, 120 volts, 92 turns, with an iron weight of 11.5 Kg.



   The construction of the type of seals shown in Fig. 92 can be used with any other shape of the core and, in Fig. 99, this type of seal applied to a core 775 in U-shape is shown, with a cylinder head 774 removable. This construction of Fig. 99 includes a U-shaped core portion 775 and a curved or demountable yoke portion 773 having a disposition such that the gasket is on the

  <Desc / Clms Page number 49>

 extension of the rectilinear parts intended to receive the coil, Each of the curves of the core comprises a sheet from one of the groups 775, as shown in FIG.



    100 and another sheet from a group 776. The sheets can be assembled in any suitable manner, for example by one of the methods already described.



  Thus a sheet 777 of group 775 will be, for example, placed with an end 778 of group 776. The ends 776 & 779 will be placed in the stop position and their opposite ends 781 & 782 will be placed in the overlapping position, so that the sheets have their joints offset, holes 783 will be drilled in the group of plates 776, offset from the center of the longitudinal axis line and, by reversing the adjacent plates in the manner already described, the joints can be offset to give the construction of the type shown in FIG. 99.



   In the constructions shown and described above the cores have been assembled with previously constructed coils, while in Fig. 101 there is shown a device for winding a conductor on two U-shaped core parts. Thus the core portions 84 & 85 are provided with rectilinear portions adjacent to each other, and when these U-shaped portions of the core are given a rotational motion, a conductor can be wound on the upright portions. to form the coil.



   Although several embodiments of the invention have been shown and described, it is obvious that it is not desired to be limited to these particular forms, given merely by way of example and without any restrictive character. that, consequently, all the variants having the same principle and the same object as the arrangements indicated above, would come within the scope of the invention as they did.


    

Claims (1)

- : ABSTRACT :- -:-:-: ...-:- The present invention relates to a new method of construction, from steel strips with optimum magnetic orientation coinciding with the longitudinal axis of the strip, of magnetic cores of the curved type for Induction devices. This new process is characterized in particular in that the sheets intended to constitute the core, being previously cut to the required dimensions, from strips of steel sheets whose optimum magnetic orientation coincides with the longitudinal axis of the strip, these cut and grouped sheets are then bent or bent by any suitable process of mechanical stress (pressure or expansion) to the shape required to constitute a magnetic circuit which is closed, <Desc / Clms Page number 50> possibly by one or more intermediate pieces, by joints with abutments, or with openings, or with entanglement, etc ... or by a combination of such joined, the mechanical stress undergone by the sheets during bending or brokering being then eliminated by an appropriate annealing and the constituent parts or core being finally assembled on or around the pre-built winding coil. 50 leaf