Abstract
An annealed amorphous metallic transformer core comprising a plurality of amorphous metallic strip packets. The plurality of amorphous metallic strip packets are shaped into a metallic transformer core. The metallic transformer core comprises a back of said core, and an overlap or front of said core. A first leg of the amorphous core extends from the back of the core to the front of the core. A second leg of the amorphous core extends from the back of the core to the front of the core. A first cap is provided along at least a portion of the first leg of the amorphous core, the cap providing straightness and/or rigidity along with dimensional thickness tolerance to the plurality of amorphous metallic strip packets contained within the leg and or back of the amorphous core.
Claims
1. A first portion of an amorphous metallic transformer core comprising; a plurality of amorphous metallic strip packets, said plurality of amorphous metallic strip packets defining a first portion of a metallic transformer core; and a first cap attached along at least a portion of said first leg of said amorphous core, said first cap providing rigidity to said plurality of amorphous metallic strip packets contained within said portion of said amorphous core.
2. The first portion of said amorphous metallic transformer of claim 1 wherein said first portion of said metallic transformer core comprises a leg portion of said core.
3. The first portion of said amorphous metallic transformer core of claim 1 wherein the first cap comprises an adhesive cap.
4. The first portion of said amorphous metallic transformer core of claim 1 wherein the first cap comprises an epoxy cap.
5. The first portion of said amorphous metallic transformer core of claim 1 wherein the first cap comprises a foldable cap.
6. The first portion of said amorphous metallic transformer core of claim 1 further comprising a second adhesive cap provided along said second leg of said transformer core.
7. The first portion of said amorphous metallic transformer core of claim 1 further comprising an epoxy provided between at least a portion of said first cap and at least a portion of said first leg.
8. The first portion of said amorphous metallic transformer core of claim 1 wherein said first cap comprises at least one longitudinally extending flap.
9. The first portion of said amorphous metallic transformer core of claim 4 wherein said first cap is provided along at least a portion of a first flap of said first cap.
10. The amorphous metallic transformer core of claim 1 further comprising an epoxy provided along at least a portion of one flap of said first adhesive cap.
11. The amorphous metallic transformer core of claim 1 further comprising a second cap provided along at least a portion of said first cap.
12. The amorphous metallic transformer core of claim 11 wherein said second cap comprises an adhesive cap.
13. The amorphous metallic transformer core of claim 12 wherein an adhesive is provided between at least a portion of said first cap and said second cap.
14. The amorphous metallic transformer core of claim 1 wherein said cap comprises an unfolded cap.
15. The amorphous metallic transformer of claim 1 wherein said first cap comprises a generally rectangular main body and at least one flap provided along a longitudinal edge of said main body.
16. The first portion of said amorphous metallic transformer core of claim 1 wherein the first cap comprises an epoxy that covers the core cast edge of the core, but is not bonded to an entire surface over which the cap covers.
17. A first portion of an amorphous transformer core comprising; a plurality of amorphous metallic strip packets, said plurality of amorphous metallic strip packets defining a first portion of a transformer core; and a bonding agent covering a limited portion of said first leg of said amorphous core, said limited application of boding agent providing rigidity and defining dimensional tolerance to said plurality of amorphous strip packets contained within said portion of said amorphous core, and dispersing weight of core legs into inner wrap material while the core is hung from said core backwall.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] Exemplary embodiments are described herein with reference to the drawings, in which:
[0062] FIG. 1 illustrates a side view of a group or a packet of metal strips for assembly into an amorphous transformer core;
[0063] FIG. 2 illustrates a top plan view of the packet of metallic strips illustrated in FIG. 1;
[0064] FIG. 3 illustrates an annealed transformer core having a joint construction, utilizing a plurality of the packet of metallic strips illustrated in FIGS. 1 and 2;
[0065] FIG. 4 illustrates a perspective view of an annealed amorphous core that has been formed with epoxy;
[0066] FIG. 5A illustrates a perspective view of one cap arrangement, that may be used to form a portion of an annealed amorphous core such as the core illustrated in FIG. 3;
[0067] FIG. 5B illustrates a side view of the cap arrangement illustrated in FIG. 5A;
[0068] FIG. 6 illustrates a perspective view of an alternative cap arrangement, that may be used to form a portion of an annealed amorphous core such as the core illustrated in FIG. 3;
[0069] FIG. 7 illustrates a perspective view of yet another cap arrangement, that may be used to form a portion of an annealed amorphous core such as the core illustrated in FIG. 3;
[0070] FIG. 8A illustrates a perspective view of another cap arrangement, that may be used to form a portion of an annealed amorphous core such as the core illustrated in FIG. 3;
[0071] FIG. 8B illustrates a side view of the cap arrangement illustrated in FIG. 8A;
[0072] FIG. 9 illustrates a perspective view of an annealed transformer core comprising a cap arrangement, such as the cap arrangement illustrated in FIG. 5A-5B;
[0073] FIG. 10 illustrates a perspective view of an annealed transformer core comprising a cap arrangement, such as the cap arrangement illustrated in FIG. 5A-5B;
[0074] FIG. 11A illustrates a perspective view of an annealed transformer core comprising an alternative cap arrangement;
[0075] FIG. 11B illustrates a side view of an alternative cap arrangement illustrated in FIG. 12A;
[0076] FIG. 11C illustrates a side view of the annealed transformer core comprising the alternative cap arrangement illustrated in FIG. 11A;
[0077] FIG. 12 illustrates an exemplary flow chart identifying certain steps for a method of shaping a portion of an annealed amorphous core, such as the core illustrated in FIG. 3;
[0078] FIG. 13 illustrates a perspective view of an annealed core prior to performing a preferred shaping method, such as the method describe in the flow chart of FIG. 12;
[0079] FIG. 14 illustrates a perspective view of an annealed core prior during an initial process step of a preferred shaping method, such as the method describe in the flow chart of FIG. 12;
[0080] FIG. 15 illustrates yet another perspective view of an annealed core prior during a process step of a preferred shaping method, such as the method describe in the flow chart of FIG. 12,
[0081] FIG. 16 illustrates another cap arrangement, that may be used to form a portion of an annealed amorphous core such as the core illustrated in FIG. 3;
[0082] FIG. 17A illustrates a joint located near an overlap or front portion of a core in an open state so as to permit a portion of the amorphous core so as to receive coils during a transformer assembly step;
[0083] FIG. 17B illustrates a method step of inserting a core into a coil window; and
[0084] FIG. 17C illustrates a method step of re-lacing a transformer joint after core insertion.
DETAILED DESCRIPTION
[0085] As is generally known in the art, an apparatus may be used to manufacture a plurality of groups or packets of amorphous metallic strips that can be further formed into a core and this core may then be used to fabricate an amorphous core transformer. As those of ordinary skill in the art recognize, transformer cores are fabricated from a plurality of grouping of stacks wherein each grouping comprises a plurality of amorphous metal strips. In one alternative preferred arrangement, transformer cores are fabricated from a plurality of groupings wherein one grouping may comprise a plurality of amorphous metal strips and wherein certain other groupings may comprise non-amorphous metal strips (e.g., grain oriented silicon steel). Still further, transformer cores may be fabricated wherein certain groupings may comprise both a plurality of amorphous strips along with non-amorphous metal strips.
Metallic Strip Packets
[0086] Specifically, and now referring first to FIGS. 1 and 2, there is shown a packet 10 of metallic strips which are manufactured by a generally known apparatus, such as the apparatus described in greater detail in U.S. Pat. No. 5,285,565. As discussed above, this packet 10 may comprise all amorphous metal strips or a combination of amorphous and non-amorphous metal strips (non-grained oriented or grain oriented). This packet 10 comprises a plurality of groups 16(a-e) of metal strips, each group comprising many thin layers of elongated strip. In this preferred illustrated packet, the packet 10 comprises five (5) groups 16(a-e) of many thin layers of elongated strips. However, those of ordinary skill in the art will recognize that other packet strip embodiments may also be used.
[0087] In addition, preferably, each group 16(a-e) may comprise a plurality of thin layers of elongated metal strips. As just one example, each group 16(a-e) comprises 15 (fifteen) thin layers of elongated strip. However, other group and strip arrangements may also be used. For example, group 16(a-e) may comprise 15 thin layers of elongated strip wherein each one of the 15 layers is uncoiled from each respective uncoiler illustrated in FIG. 1. For example, the first layer 16a may be uncoiled from a first uncoiler, the second thin layer may be uncoiled from a second coiler, etc.
[0088] In each group, the layers of metallic strips have longitudinally-extending edges 18 at opposite sides thereof and transversely-extending edges 20 at opposite ends thereof. In each group 16a-e, the longitudinally-extending edges 18 of the strips at each side of the group are aligned. In addition, in each group 16a-e, the transversely-extending edges 20 of the strips at each end of the group are aligned. In the illustrated packets of FIGS. 1 and 2, the groups 16 are made progressively longer beginning at the bottom of the packet 10 (or inside of the packet 10) and proceeding toward the top of the packet (or toward the outside of the packet 10).
[0089] The increased length of these groupings of the metallic strips enables the groups 16(a-e) to completely encircle the increasingly greater circumference of the transformer core form as the core form is built up on the winder section, that is, when the plurality of packets are wrapped about an arbor illustrated in FIG. 1. As described in greater detail below, these packets are wrapped about an arbor with their inside, or shortest, group nearest the arbor. That is, as just one example, for the metallic strip packet 10 illustrated in FIGS. 1 and 2, this packet will be wrapped about the arbor with the inside or shortest metallic group 16e nearest the arbor (i.e., nearest the inner diameter of the transformer core).
[0090] Referring still to FIGS. 1 and 2, adjacent groups in each packet 10 have their transversely-extending ends 20a -e staggered so that at one end of the packet the adjacent groups underlap, and at the other end of the packet the adjacent groups overlap. For example, adjacent groups 16a and 16b have their transversely-extending ends staggered so that at one end of the packet the adjacent groups underlap, and at the other end of the packet the adjacent groups overlap. This staggering results in distributed type joints in the final core after they have been wrapped about an arbor.
[0091] FIG. 3 illustrates a transformer core 40 that may be manufactured from a plurality of strip stacks, such as a plurality of strip stacks illustrated in FIGS. 1 and 2. As illustrated, this jointed core 40 includes a plurality of spirally wound metallic strip packets that may be initially wound as on a round or rectangular mandrel. The circumference of the circular mandrel or the parameter of a rectangular mandrel is determined by the size of a core window 42 desired to accommodate the high and low voltage coils of a finished transformer. Similarly, the number of spirally wound metallic strip packets is determined by the ultimate power rating of the transformer and a design-specified maximum buildup dimension for a core leg. For example, typically the buildup dimension defines the core leg thickness and hence the overall transformer design is based on a specific cross sectional area that assumes a density factor for the amorphous metal material. However, as those of ordinary skill in the art will recognize, the number of desired amorphous metal strips may be determined by a particular electrical characteristic, electrical property, or a desired dimension of the amorphous metal core as will be described in greater detail herein.
[0092] The core must be provided with a support fixture that provides core support and core containment during subsequent annealing and testing procedures. For example, referring now again to FIG. 3, the magnetic core, generally designated 40, includes a plurality of individual metallic strip packets that have been cut to form a joint 62. As illustrated, the plurality of amorphous metallic strip packets are shaped into a metallic transformer core 40, wherein the metallic transformer core comprises a back end or closed end 46 and an overlap or front portion or end 50 of the core 40. A first leg 54 of the amorphous core extends from the back 46 of the core to the front of the core while a second leg 58 also extends from the back of the core to the front of the core.
[0093] Because of the flexibility of the amorphous metal strip packets, one or more support fixtures 64, 80 may be employed so as to maintain the overall integrity and shape of the annealed core 40. For example, in this illustrated support fixture arrangement, the first support fixture 64 comprises two long outer support plates 66, 68, two long inner support plates 72, 74, two narrow outer support plates 78, 80, and two narrow inner support plates 84, 86. Additionally, a second support fixture 90 in the form of a metallic band is provided along the outer circumference of the core and holds the various support plates of the first support fixture 64 in place.
[0094] As illustrated in phantom at 98, a joint 62 located near the overlap or front portion 50 of the core permits a portion of the amorphous core 40 (also referred to as the overlap of the core) to be opened so as to receive coils during a transformer assembly. As best illustrated schematically in FIGS. 1 and 2, the packets are divided into a plurality of groups of packets and several sets of groups of packets. In FIGS. 1 and 2, approximately 7 laminations have been illustrated as defining a group of laminations but it should be understood that the number of metallic strips in a group could be from between about 5 and 30 metallic strips and is preferably approximately 30 metallic strips. As previously discussed, each group of metallic strips is offset laterally from its adjacent group of metallic strips and a certain number of these groups of strips are defined herein as a set of groups. In the illustration of FIGS. 1 and 2, three groups of strips constitute a set of groups but it should be understood that the number of groups of strips in a set of groups of strips may be typically between about 5 and 25 groups before it is necessary to step back or forward with respect to the direction of the spiral to repeat the sequence. The number of groups of strips in a set of groups is essentially controlled by the length of the first leg 54 of the rectangular core before that first leg begins to curve to form the first and second side legs 56, 60 of the magnetic core 40.
[0095] Once the core, such as the core and support structure illustrated in FIG. 3, has been annealed, the core will undergo certain electrical testing (as generally described above) while the support fixtures 64, 90 remaining in place. Assuming that the annealed core passes these various electrical tests, the support fixtures 64, 90 must then have to be removed so that the tested annealed core can be formed or shaped so that it retains its annealed shape as the core is prepared to be shipped or assembled into a transformer.
[0096] In one preferred method of maintaining the annealed core in its desired annealed shape, one or more caps may applied over at least portion of at least one of the legs of the core. That is, in reference to the core illustrated in FIG. 3, one preferred method of maintaining the annealed core in its desired annealed shape, is to provide a least one cap over at least portion of an upper surface or a cast end the first leg 54 of the core 40.
[0097] As just one example, FIG. 5A illustrates one such cap 100 that can be used to shape a transformer core, such as the core 40 illustrated in FIG. 3. As noted above, in one arrangement, such a transformer core 40 may comprise an annealed transformer core. For example, in such an annealed transformer core, the amorphous strips making up the core may undergo an annealing process before formation of the core, after formation of the core, or both before and after the formation of the core.
[0098] As shown, the cap 100 comprises a generally rectangular shape and comprises a main body 102 extending along a length of the main body that is represented by L.sub.mb 122. Preferably, the main body length L.sub.mb 122 of the generally rectangular cap is generally equivalent to the length of one of the legs of the annealed core, such as the length of the first leg 54 of core 40.
[0099] As those of ordinary skill in the art will recognize, the cap 100 may comprise alternative lengths, sizes and/or shapes. As just one example, the cap 100 may comprise just a main body 102 without either a first longitudinal extending flap 106 or a second longitudinal extending flap 110.
[0100] As yet another example, the presently disclosed cap arrangements may be used with single phase or three phase (i.e., Evans style) transformers. For example, in a typical three phase transformer design, the transformer comprises basically two smaller cores of equal size diameter and cross-sectional area, together encircled by a larger core of equal cross-sectional area. In such a configuration, a single cap arrangement (such as the cap 100 illustrated in FIG. 5A) may be used to provided stability and/or dimensional definition to both a first leg of a first core and an adjacent first leg of a second core. The first leg of the second core may comprise either a leg of the smaller encircled core or a leg of the larger core of equal cross-sectional area.
[0101] As illustrated in FIG. 5A, the cap main body 102 comprises two main body long creases 114, 118 that define a first longitudinally extending flap 106 and a second flap longitudinally extending flap 110. As just one example, the two main body long creases 114, 118 may be formed by running a razor or other blade or cutting element along the length of the main body 102 so as to create a shallow score, or an intermittent cut. Additionally, a crease may be formed in the cap material by compressing, or embossing, the material with a straight fold line. This may be accomplished by pressing the cap material between a narrow blade and a drum with application of a constant pressure of the narrow blade against the cap material. Preferably, the cap 100 may be produced by folding the edges such that a width of the main body represented by W.sub.mb 128. More preferably, width of the main body represented by W.sub.mb 128 is designed to match the specified maximum buildup dimension for a transformer core leg.
[0102] In one preferred arrangement, the cap 100 may be produced from an oil-compatible, paper-like material that will accept being folded so that the material maintains a sharp edge. In a preferred arrangement, the cap 100 comprises an insulation material, such as a Nomex® insulation material. Such an insulation material may preferably comprise a Nomex® paper having a thickness from approximately 0.005″ to approximately 0.050″.
[0103] The cap 100 may comprise a piece of material that covers the amorphous core along the cast edge of the amorphous material and attached to both the inside and outside of the core on either side of the cast edge. Further, the cap 100 may be attached to the cast edge using some type of adhesive or an adhering mechanism—such as tape, glue, epoxy, mechanical stitching, etc. or some combination thereof. In one preferred arrangement, the cap may be fixedly attached to the outer sides of the core legs and backwall using double sided tape. Such an adhesive prevents the cap material (and perhaps an over cap material as will be discussed with respect to FIGS. 11A-C) from being easily detached from the sides of the core. One advantage of using such a cap is that the cap (i.e., the cap main body width W.sub.MB) provides a limit to an amount of core wall expansion so that the maximum buildup stays within a desired specification. This may be accomplished without applying any unnecessary pressure when the core leg is straight—as it is when the core is installed in the transformer coil. As such, by using a cap having a constant main body width W.sub.MB, the resulting batch of annealed cores will result in a greater performance consistency from core to core within the batch. Additionally, a cap may be attached to a bonding material applied to the outer edges of the cast ribbon edge using an adhesive or double-sided tape.
[0104] As such, the material wall is allowed to expand to maximum buildup (BU) dimension, which reduces stresses in the amorphous packets, resulting in better overall core and therefore transformer performance. This can also reduce or eliminate the need for inserting stuffing between the core wall and the end wall in the transformer. Since the overall core portion width is quite exact and repeatable, a slight interference fit can be designed for core and coil which therefore can eliminate the need for stuffers.
[0105] Another advantage of such a cap configuration is that the core will be more easily inserted into the coil. If packing is necessary to wedge between core leg and coil wall, it will now be easier to insert wedges as there will be no hanging up on uneven areas of the core wall that may sometimes arise if an epoxy layer is used. For example, taped core walls can be misshapen (i.e., they may be crooked or not straight) Forcing crooked or not straight legs into straight coils can induce stresses in the collection of amorphous ribbon thereby causing core performance losses.
[0106] Once the cap 100 is folded so as to form a crease between the main body 102 and the first and second longitudinal flaps 106, 110, the cap can be pushed onto a long edge of the core, and then affixed using a piece of tape. However, in one alternative arrangement, an epoxy, tape gum, double sided tape, combination thereof, or alternative adhesive may be applied to at least a portion of an underside of the cap before the cap is affixed to the annealed core. For example, as illustrated in FIG. 5A, a first bead 134 of an epoxy or alternative adhesive may be applied to the first long extending flap 106 and a second bead 140 of an epoxy or alternative adhesive may be applied to the second flap 110. Alternatively, and as illustrated in FIG. 6, a first bead 150 of an epoxy or alternative adhesive may be applied along the main body 102 of the cap 100.
[0107] One important aspect of the cap 100 is the sharp bends or folded creases 114, 118 that define the first and second longitudinally extending flaps 106, 110. One advantage of such sharply defined bends is that they allow a core manufacturer to quickly and efficiently locate and line up the edge of the core leg and apply the cap 100 in a minimum of time in an exact location. This will allow the amorphous material in the core leg to experience the smallest amount of compression required to meet the maximum buildup specification.
[0108] FIG. 7 illustrates yet another alternative cap arrangement. In yet another alternative embodiment, and as illustrated in FIG. 7, the cap 100 may be affixed to the leg of the core with a combination of both an amount or a bead of an epoxy and/or an amount or a bead of an adhesive. As just one example, and as illustrated in FIG. 7, a first bead 160 of an epoxy may be provided along the first longitudinal crease 114 of the cap 100 and a second bead 164 of an epoxy may be provided along the second longitudinal crease 118 of the cap 100. In addition, a first amount or a bead 168 of an adhesive may be provided along the first longitudinally extending flap 106 and a second amount or bead 174 of an adhesive may be provided along said second longitudinally extending flap 174 of the cap 100. With such an arrangement, once the adhesive and the epoxy cures, since both the adhesive and the epoxy reside only on outside edges of the cast edge of the core leg, the core leg to experiences the smallest amount of compression required to meet the maximum buildup specification while also allowing the amorphous core to achieve its desired magnetostrictive motion.
[0109] FIG. 8A illustrates yet another alternative cap arrangement 180 that can be used to shape an annealed transformer core, such as the core 40 illustrated in FIG. 3. FIG. 8B illustrates a side view of the alternative cap arrangement 180 illustrated in FIG. 8A.
[0110] Referring now to both FIGS. 8A and 8B, and similar to the cap arrangement 100 illustrated in FIG. 5A, this alternative cap arrangement 180 comprises a generally rectangular shape and comprises a main body 184 extending along a length of the main body and may be represented by L.sub.MB 190. Preferably, the main body length L.sub.MB 190 of the generally rectangular cap is generally equivalent to the length of one of the legs of an annealed core, such as the length of the first leg 54 of core 40 illustrated in FIG. 3. As those of ordinary skill in the art will recognize, the cap 180 may comprise alternative lengths, sizes and/or shapes.
[0111] As illustrated in FIG. 8A, and in contrast to the cap arrangement 100 illustrated in FIG. 6A, the cap main body 184 comprises one long crease 194 that defines a first longitudinally extending flap 196 and generally comprises an L-shaped cap. Preferably, where the cap 180 comprises a foldable, a workable, or a malleable material, the cap 180 may be produced by folding an edge of the flap 196 such that the now defined crease 194 defines a width of the main body represented by W.sub.MB 200. In one preferred arrangement this main body width W.sub.MB 200 will be generally equal to a specified maximum buildup dimension for the core leg. Alternatively, this main body width W.sub.MB 200 will be generally less than a specified maximum buildup dimension for a core leg. In such a situation where the width of the main body W.sub.MB 200 is less than the maximum buildup dimension, and as discussed below, two cap arrangements 180 may be used along the leg of a core where the cap arrangements 180 are placed one over the other with the respective flaps facing one another.
[0112] One advantage of using cap 180 comprising a single flap is that is may be used with smaller core configurations and hence a smaller leg core width. In addition, in one cap configuration, two such L shaped caps may be used where a first alternative cap 180 is provided along the cast edge of the core with the flap 196 extending along the inner surface of the core leg. Similarly, a second such L shaped alternative cap 180 may be provided along the main body with the flap 196 extending along the outer surface of the core leg. In such an arrangement, the first cap 180 may comprise a piece of material that covers the amorphous core along the inner cast edge of the amorphous material and the second cap 180 may comprise a piece of material that covers the amorphous core along the outer cast edge of the amorphous material.
[0113] One advantage of using such a multiple cap arrangement is that it provides a limit to the amount of core wall expansion so that the maximum buildup stays within a desired specification. This may be accomplished without applying any unnecessary pressure when the core leg is straight—as it is when the core is installed in the transformer coil.
[0114] As those of ordinary skill in the art will recognize, alternative epoxy and adhesive methods may also be used to fixedly attach the cap to the leg of the transformer core.
[0115] After the epoxy and/or adhesive has been applied to the cap or multiple caps, the cap or multiple caps may then be affixed along a leg of the annealed core. For example, FIG. 9 illustrates a cap (such as the cap 100 illustrated in FIG. 5A) affixed along a first leg 54 of an annealed amorphous core, such as the core 40 illustrated in FIG. 3. As illustrated in FIG. 9, the cap 100 is affixed along the first long leg 54 of the core with the first longitudinal extending flap 106 extending along an inner surface of the core and the second longitudinal extending flap 110 extending along the outer surface of the core 40. Advantageously, the cap 100 is affixed along the long leg of the core 40 with the first longitudinal extending flap 106 extending along the inner surface and the main body 102 of the cap is affixed along the cast edge of the core such that the first longitudinal crease 114 between the main body and the first flap maintains the straightness of the core inner surface. Similarly, the cap 100 is affixed along the long leg of the core 40 with the second longitudinal extending flap 110 extending along the outer surface of the core such that the second longitudinal crease 118 between the main body 102 and the second flap 110 maintains the straightness of the core inner surface while still allowing the core to achieve a certain level of magnetostrictive forces induced by the core.
[0116] One advantage of using such a cap 100 is that the first and second creases or bends 114, 118 allows a user to locate the caste edge of the core leg 54 and to apply the cap 100 in a minimum amount of time in an optimum location. Optimum cap placement along the leg cast edge allows the amorphous material of the core leg to experience the smallest amount of compression required to meet the maximum buildup specification.
[0117] Another advantage of the cap is that the cap provides a limit to the amount of core wall expansion so that the buildup stays within a certain desired specification, without applying any unnecessary pressure when the leg of the core is straight—as may occur when the core is installed in the transformer coil.
[0118] As also illustrated in FIG. 9, tape may be used to further secure the cap to the core. For example, where an adhesive and/or epoxy is provided on the cap main body and/or the cap flaps, tape may be used to properly secure the cap before the adhesive or the epoxy cures. As just one example, tape 212 can be provided along the outer surface of the cap, for example, at the front end of the core as well as at the back end of the core. In addition, tape 216 may be used to secure a bottom portion of the longitudinal flap 110 and along the outer surface of the core leg 54. One advantage of using tape in this method is that it allows the transformer core to be moved and further processed while any of the epoxy or adhesive cures. Alternatively, a double sided adhesive (e.g., a double sided tape) may be used between the top surface of the core and the cap.
[0119] FIG. 10 illustrates a perspective view of an annealed core comprising a first and a second cap. As can be seen, the annealed core is provided with a first cap (such as the cap illustrated in FIG. 5A provided along a first core leg and a second cap (such as the cap illustrated in FIG. 5A) along a second core leg. As those of ordinary skill in the art will recognize, alternative cap arrangements may be used on a single transformer core. As just one example, the annealed core illustrated in FIG. 10 may be provided with a first cap (such as the cap illustrated in FIG. 6A provided along the first core leg and the second cap (such as the cap illustrated in FIG. 7, 8, or 9A) along the second core leg.
[0120] As can also be seen from FIG. 10, an area on the left side which is the “back” of the core which cannot be opened in the same fashion as can the end that is laced (the overlap of the core). Preferably, the back of the core will be covered with some type of material so as to prevent amorphous chips from escaping from the core (and perhaps, into a fluid of a transformer). In this preferred arrangement, the back of the core is provided with various strips of tape, or coated with an adhesive and/or epoxy. Alternatively, the back of the core could be taped in a similar manner, where the edges of the cap are covered with the tape.
[0121] If it is determined that a greater cap rigidity is desired or specified for a particular size transformer core, then a thicker cap material can be applied. As just one example, the cap material may comprise an insulation material comprising a thickness from approximately 2 to approximately 30 mils. Additional rigidity may also be obtained by depositing a bead of epoxy along an inside of the cap before the cap is placed on the core leg as described above.
[0122] Yet another alternative core shaping arrangement may be used for more core stability. For example, FIG. 11A illustrates a perspective view of yet another alternative amorphous core cap arrangement 242 for shaping an annealed core 258, such as the core illustrated in FIG. 3. For example, FIG. 11A shows an alternative amorphous core cap arrangement 242a comprising a first cap 244 and a second cap 250 where the second cap 250 is positioned over the first cap 244, preferably positioned in a piggy-back style along at least a portion of the first cap 244. In one preferred arrangement, the core 258 may be provided with three such cap arrangements 242 along a top surface of the core: two such cap arrangements 242 a,c provided along the first and second long legs of the core and a third such cap arrangement 242b provided along the side leg or back side of the core.
[0123] Specifically, and as shown in FIG. 11A, a first cap 244a is provided along a cast edge 256 of a first core leg 260 of the core 258. A second cap 250 is then placed over at least a portion of the first cap 244, essentially holding the first cap 244 in place. In this alternative piggy-back type cap arrangement 242a, the first cap 244 resides along the top surface of the first leg 260 of the transformer core, similar to the first cap 100 illustrated in FIG. 5A. Alternative first cap and epoxy/adhesive combinations and arrangements, such as those herein described and illustrated for example in FIGS. 6-8 may also be used to affix the first cap 244 and/or the second cap 250 to the core 258.
[0124] In FIG. 11A, the first cap 244 preferably comprises a non-conductive material, such as an insulation material, such as a Nomex® paper. Preferably, the second cap 250 comprises a cap having certain ductile or pliable properties. More preferably, the second cap 250 comprises a metallic cap and comprises both a first longitudinally extending flap 252 and a second longitudinally extending flap 254, similar to the cap arrangement 100 illustrated in FIG. 5A. For example, such a metallic cap may comprise grain-oriented silicon steel, cold-rolled steel, galvanized, or any metal or composite offering strength.
[0125] FIG. 11B illustrates a side view of one arrangement of a preferred second cap 250 that can be used with the cap arrangement illustrated in FIG. 12A. As illustrated in FIG. 11B, the second cap 250 comprises a main body 252 with the first flap and the second flat 252, 254 extending therefrom. In one preferred arrangement, the first and second flaps 252, 254 of the second cap 250 are biased inwardly or towards one another. In this manner, when the second cap 250 is placed on at least a portion of the first cap 244, the first and second inwardly biased flaps 252, 254 compress or exert an inwardly directed force onto the first cap flaps 246, 248 thereby retaining both the first cap and the second cap in place along the first leg 260 of the core 258. In one preferred arrangement, a small amount of epoxy and/or adhesive may be provided between the second cap 250 and the first cap 244 and/or between the first cap 244 and the cast edge 256 of the first leg 260. In another preferred arrangement, a double sided adhesive may be provided between the second cap 250 and the first cap 244 or between the first cap 244 and the cast edge 256 of the first leg 260 or between the cap and the core wall.
[0126] FIG. 11C illustrates a cross sectional view of the first and second cap arrangement illustrated in FIG. 11A. FIG. 11C illustrates a side view of the piggy back cap arrangement with the second cap 250 seated over the first cap 244. As illustrated, the first cap 244 has both a first and a second cap of length L.sub.FC 234. Similarly, the second cap comprises a first and a second flap having a length L.sub.SC 236. As illustrated, the length of the first and second flap L.sub.FC 234 of the first cap 244 is longer than the length of the first and second flap L.sub.SC 236 of the second cap 250. As can be seen from FIGS. 11B and C, the first and second flaps of the second cap are configured to provided an inwardly directed bias so as to maintain a pressure upon the first cap (and hence the width of the leg of the core) when disposed over the first cap.
[0127] Providing such an overlapping second cap arrangement 242 provides certain advantages. For example, one such advantage of such a dual cap configuration is that such a configuration (for certain sized annealed cores) may not require the use of tape for either the first cap or the second cap. Providing such a cap arrangement therefore results in labor savings as well as cost savings during the core shaping process.
[0128] Alternatively, if epoxy and/or adhesive were to be applied inside the first cap 244, the double cap can be placed on the core without the need for taping the cap to the core. If epoxy and/or adhesive were applied, the inwardly created pressure of the first and second cap flaps 252, 254 of the second cap 250 can be configured and dimensioned so as to hold the first and second caps in place until the epoxy cures.
[0129] Preferably, when a metal over-cap is used, the length of the paper cap flaps should be longer than the length of the metal cap flaps. For example, returning to FIG. 11A, as illustrated, the length of the first paper cap flap is slightly longer than the length of the first metal cap flap that overlaps the first paper cap flap. In this manner, the metal over cap will be electrically insulated from the steel that is provided along the outside of the core. If the metal in the cap were to come into direct contact with the silicon steel, a short could be created.
[0130] FIG. 11A illustrates three similar dual cap arrangements 242 provided along the first and second legs and the short legs. However, as those in skill in the art will recognize, alternative cap arrangements may be used along the various legs of the core. As just one example, the cap arrangement illustrated in FIG. 5A may be used on the short leg of core 258 illustrated in FIG. 11A while the dual configuration 242 may be used along the long legs of the core 258 (as illustrated). Other alternative cap arrangements as disclosed herein may also be used.
[0131] The following describes one preferred method for utilizing a plurality of caps to form and shape a metallic amorphous annealed core. For example, FIG. 12 illustrates one exemplary flow chart 300 illustrating certain process steps that may be undertaken for forming or shaping an annealed amorphous core comprising at least one cap, such as those cap arrangements described in detail herein. For example, at a first process Step 302, the amorphous core is annealed and then tested for certain electrical properties. FIG. 13 illustrates such a core that has been annealed, that has passed its electrical tests, and is now ready to be shaped and formed for transportation. The annealed core 400 is shown with a first support fixture 374 (comprising a wire cable) and a second support fixture 390 (comprising a plurality of support plates 366, 368, 372, 374, 378, and 380).
[0132] At the second process Step 304, the annealed core 400 is placed on risers. Such a process Step 304 is illustrated in FIG. 14 where the core 400 is places on risers 370a,b. As illustrated in FIG. 14, an annealed core 400 is placed so that the core's front end (i.e., its lacing end) 350 and its back end (i.e., its back wall) 346 sits upon risers 380 that reside along a work surface. (For ease of explanation, the support plates have been omitted from FIGS. 14 and 15). Preferably, this work surface comprises a turn-table. The risers 380a,b lift a bottom portion of the annealed core off of the work surface. Lifting the bottom surface of the core off of the work surface allows open access to both the first and second bottom sides of the annealed core.
[0133] Then, as illustrated in Step 306 in flow chart 300, the first and second outer support plates 366, 368 and the first and second inner support plates 372, 374 forming the various walls of the core are then raised in the direction away from the work surface. As just one example, these support plates may be raised approximately 1.0″ to about 2.0″ from their annealed position (as illustrated in FIG. 13) so as to expose enough of the bottom edge of the core to allow cap placement. Raising the support plates in this amount of distance allows access to the first and second bottom legs of the core while maintaining the containment and shape of the core.
[0134] At Step 308, a first and a second cap 380a,b may be attached to a bottom surface of the first and the second legs 354, 358 of the core, respectively. The first and second caps 380a,b may be attached as described herein. For example, as illustrated in FIG. 14, a first cap 380a is illustrated as being attached to a bottom surface of the first leg 354 and a second cap 380b is illustrated as being attached to a bottom surface of the second leg 358.
[0135] Once the bottom first and second caps have been attached at Step 308, at Step 310, the outer band 374 holding the outer support plates in place can be cut and removed, thereby allowing the outside support plates to be removed. This step is illustrated in FIG. 14 where the annealed core is now shown with the first and second caps provided along the bottom case edges of the first and second legs of the core.
[0136] Then, at Step 312, one wall at a time, an outer flap of the first top cap is located and attached to the outside of the each wall of the annealed core. For example, the outer flap of a first top cap is attached to the outside of the first wall and the outer flap of a second top cap is attached to the outside of the second wall. Thereafter, at Step 314, the first and second inner plates 372, 374 can then be removed by being pulled up, and removed from the window 342 of the core 400. Then, one at a time, at Step 316, the inner flaps of the first and second top caps can then be attached to an inside surface of each respective wall of the core.
[0137] As described herein in detail, an adhesive and/or an epoxy may be utilized to provide a heightened degree of stability to the cap arrangement utilized to shape a specific portion of the core. Returning to the method illustrated in FIG. 12, if it is determined at Step 318 that an adhesive and/or epoxy has been placed on the cast edge of the core, then the process would proceed to Step 320. An adhesive or an epoxy may be applied manually using an epoxy mixing system, syringe, or other means in a pattern that is designed to provide wall stability. At Step 320, if an adhesive and/or epoxy is placed on the cast edge of the core, then it is preferable to place one or more spacers inside the core window, between the two inner most walls of the core to as to keep the side walls straight until the adhesive and/or epoxy cures. These spacers can serve to keep the legs of the core straight and parallel to one another until the epoxy is cured.
[0138] Accordingly, Applicants' presently proposed method and apparatus is directed to shaping or forming an amorphous metal transformer core that is cost effective to manufacture, that has low energy losses, that is energy efficient, and is more environmentally friendly than other known methods. Applicants' disclosed methods and apparatus is also directed to an amorphous metal transformer core in which the difficulties of handling, processing, and shaping the amorphous metal cores to perform the manipulative steps of the fabrication process are reduced and the mechanical stresses induced into the amorphous metal strips and hence the core during its fabrication process are reduced. As such, the disclosed methods and apparatus allows the amorphous ribbons to move in response to the magnetrostrictive forces induced by a transformer conductor coil and therefore increases overall transformer core performance. In addition, the presently disclosed systems and methods of shaping and forming of the amorphous metal core process is simplified since it does not require the labor intensive steps of taping, providing an epoxy, and repeated curing of the epoxy. As such, the presently disclosed methods and apparatus eliminates certain costly and labor intensive steps as discussed in greater detail above.
[0139] Exemplary embodiments of the present invention have been described. Those skilled in the art will understand, however, that changes and modifications may be made to these embodiments without departing from the true scope and spirit of the present invention, which is defined by the claims.
[0140] As just one example, the cap material may be selected from any suitable material for an amorphous metallic transformer core presently known in the art or later developed. Such materials may comprise a pliable material, an insulating material, a workable material and/or an adhesive material. For example, the cap material may comprise at least one of a thermoplastic material, a textile material, an insulation material, or an adhesive strip, such as a strip of tape.
[0141] As just one example, an alternative amorphous core cap may comprise a thermoplastic material, such as a thermo-softening plastic, or other similar polymer that becomes pliable or moldable above a specific temperature and returns to a solid state upon cooling. With such a thermoplastic cap arrangement, while keeping the forming support plates on the amorphous core during the capping process so as to maintain wall straightness and buildup, an epoxy or alternative adhesive may deposited on the cast edges where the thermoplastic material is to be placed. The areas with adhesive may then be covered with a strip of a thermoplastic material. In one preferred arrangement, the strip of thermoplastic material may be slightly wider than the wall buildup centered along the wall length, corners, and backwall. The amorphous core with the thermoplastic cap may then placed under a heating element in order to melt the thermoplastic material. In such a manner, the edges of the thermoplastic material will preferably overhang the core wall and bend over against the core wall. Once melted, the core may then be cooled. The core can then be flipped over and this thermoplastic capping process may be repeated on the other side core. The thermoplastic material may also be trimmed to the dimensions of a preferred buildup, if desired.
[0142] In yet another alternative cap arrangement, a cap may comprise a heavy textile material, such as canvas or other similar cloth or flexible woven material. Similar to the thermoplastic cap arrangement generally described above, while keeping the forming and support plates on the core so as to maintain wall straightness and buildup, an epoxy or an alternative adhesive may be placed on the cast edge of the core where the textile material is to be placed. Once the adhesive has cured, an overhang material may be attached to the core wall with adhesive, or trimmed away.
[0143] In yet another alternative cap arrangement, a cap may be formed using a heavy textile material as discussed above but in this arrangement, the textile may be attached to the core using adhesive only on a flap or flaps of the textile cap. The forming or support plates may be kept on the core during the capping process so as to maintain wall straightness and buildup as discussed herein.
[0144] In yet another example, a piece of tape, or other material through which epoxy or other bonding agent cannot pass, may be applied to a portion of the center core legs or backwall or both and epoxy or other bonding or fixative agent can be applied to the cast edge of core legs and backwall. Once the bonding agent has cured or hardened, the portion of the cast edge that was covered with the tape or other material will be allowed magnetostrictive motion. Such a core would then have limited performance degradation resulting from the shaping process and method.
[0145] As just one example, an alternative amorphous core cap may comprise an adhesive cap such as one comprising a strip of tape. In such a cap arrangement, one or more strips of an adhesive tape may be provided along various portions of the core, such as along at least a portion of one or more legs and/or the yoke. In one such adhesive cap arrangement, an epoxy may be applied in an “S” or complete or partial sinusoidal pattern(s) along one or more top surfaces of the core. The adhesive cap may then be applied over this core portion. The adhesive cap attaches to the silicon inner and outer wall of the leg, as generally described above with respect to cap 100 and FIG. 9, so as to provide a certain degree of dimensional control and mechanical stability to this particular portion of the core.
[0146] One advantage of such an adhesive cap is that such a cap helps to prevent amorphous chips from exiting the capped core. In addition, the epoxy underlying the adhesive cap provides increased core mechanical stability. With such an arrangement, once the underlying adhesive and/or the epoxy cures, since both the adhesive and the epoxy reside only on outside edges of the cast edge of the core leg, the core leg experiences a minimal amount of compression required to meet the maximum buildup specification while also allowing the amorphous core strips within the leg to achieve its desired magnetostrictive motion.
[0147] As just one example, FIG. 16 illustrates one such adhesive cap 600 that can be used to shape a portion 630 of an annealed transformer core, such as one or more legs of the core 40 illustrated in FIG. 3. As shown, the adhesive cap 600 comprises a generally rectangular shape and comprises a main body 602 extending along a length of the main body that is represented by L.sub.MB 622. Preferably, the main body length L.sub.MB 622 of the generally rectangular adhesive cap 600 may be generally equivalent to the length of one of the legs of the annealed core, such as the length of the first leg 54 of core 40. The adhesive cap 600 may also comprise a main body 602 along comprising a first longitudinal extending flap 606 or a second longitudinal extending flap 610.
[0148] As those of ordinary skill in the art will recognize, the adhesive cap 600 may comprise alternative lengths, sizes and/or shapes. As just one example, the cap 600 may comprise just a main body 602 without either a first longitudinal extending flap 606 or a second longitudinal extending flap 610.
[0149] More preferably, a width of the main body represented by W.sub.MB 628 is designed to generally match a specified maximum buildup (BU) dimension for a transformer core leg. For example, the main body width W.sub.MB 628 may be designed to match the specified buildup (BU) 629 of the transformer core portion 630.
[0150] In one preferred arrangement, the adhesive cap 600 may be provided with a dimensional indicator near either one or both edges wherein a space or distance between these indicators corresponds generally to a core buildup (BU) dimension of the transformer core portion. For example, as illustrated in FIG. 16, the adhesive cap 600 comprises a first dimensional indicator 614 and a second dimensional indicator 618 wherein the space or distance W.sub.MB 628 between these dimensional indicators 614, 618 corresponds to the core buildup (BU) dimension 629 of the transformer core portion 630. The dimensional indicators may be marked with pen, paint, marker, or any other similar inscribing agent. Additionally, the adhesive cap 600 may also be embossed with a crease to ease cap application and define buildup dimension.
[0151] The adhesive cap 600 may be applied by first applying one edge 606 of the cap 600 to the silicon inner sheet of the core portion, lining up the first dimensional indicator 614 with an edge of a silicon steel 632 of the core portion 630. Depending on the cap material selected, the cap 600 may then be stretched over, drawn across or pulled over the epoxied area of the core portion 630 and attached such that the second dimensional indicator 618 on the cap 600 aligns with an outer silicon steel edge 634 of the core portion 630.
[0152] After the adhesive cap has been applied over the epoxy, an operator can then smooth out the epoxy under the adhesive cap by hand, or through use of a roller, spatula, or by some other similar smoothing device. Thereafter, the partially capped core can then be flipped, and the core capping method may be repeated. (See, e.g., FIGS. 13-15 and supporting text). As discussed in greater detail herein, the support plates may then be removed, the capped core can then be tested, and then placed in a shipping container where the epoxy will cure at room temperature, typically within 24 hours. One advantage of using such an adhesive cap and epoxy capping method is that no additional heating of the core is required to obtain a capped and epoxied, annealed core.
[0153] In one adhesive cap arrangement, the adhesive cap 600 may comprise reinforcement strands 650. As illustrated in FIG. 16, such strands 650 may be provided that run along the length of the main body 602. Alternatively, such strands 650 maybe provided running perpendicular to the rolling direction (90 degrees offset from that direction illustrated in FIG. 16).
[0154] There are a number of advantages of using such an adhesive cap, such as cap 602. For example, an adhesive cap can limit the maximum buildup size of an amorphous core leg and back wall. In addition, such an adhesive cap arrangement allows the individual amorphous ribbons making up the core portion to move independently of adjacent ribbons at the amorphous cast edge. As such, an adhesive cap restricts, but does not prevent parallel movement of amorphous ribbons from one another.
[0155] Moreover, an adhesive cap helps to maintain a maximum dimension for core leg and/or back wall buildup while an epoxy, glue, or other fixative material cures. After curing, portions of the adhesive cap, or in some applications the entire adhesive cap itself, may be removed. For increased core leg strength, the entire cast edge (core top/bottom) with exception of lacing area may be epoxied and tape or other material capable of maintaining buildup dimension placed on the core. This way, no curing process is required as the uncured epoxy is contained by the cap material. Neither edge masking nor edge trimming is necessary. This method will not take advantage of the performance gains resulting from allowing the amorphous sheets magnetostrictive motion.
[0156] An amorphous core having walls with intermittent application of epoxy applied to the cast ribbon edge so as to add structure stability to the core, while still allowing enough movement of the amorphous ribbon to allow magnetostrictive motion. The amount of epoxy applied will affect, though not necessarily linearly, the electrical performance of the core. Application of epoxy, glue, or other fixative agent, either completely or partially covering the back wall area to prevent compression of the amorphous sheets in the back wall area. Cap material should be flexible material but resistant to stretching.
[0157] As noted previously, the handling, processing, fabrication, annealing and shaping of wound amorphous metal cores presents certain unique manufacturing challenges of handling these thin metallic strips. This is particularly present throughout the various manufacturing steps of winding the core, cutting and rearranging the core laminations into a desired joint pattern, annealing and then shaping the core, and finally lacing the core through a window of a preformed transformer coil.
[0158] For example, as noted herein, one common transformer core manufacturing procedure is to wind the core independently of the transformer preformed coil and/or coils with which the cores will ultimately be linked. In such manufacturing procedure, the amorphous core is formed with a joint (such as the joint 62 illustrated in core 40 illustrated in FIG. 3). At this joint, the core laminations may be separated from one another so as to open the amorphous core 40 to thereby accommodate insertion of a transformer core into a coil window. For example, FIG. 17A illustrates the joint 62 located near the overlap or front portion 50 of the core in an open state so as to permit a portion of the amorphous core 40 (also referred to as the overlap of the core) to receive coils during a transformer assembly.
[0159] FIG. 17B illustrates a method of inserting the core 40 into a coil window. After insertion into the coil window, the opened up core can then closed to remake the joint. FIG. 17C illustrates relacing the joint after core insertion. As those of ordinary skill in the relevant art will recognize, this procedure is commonly referred to as “lacing” the core with a coil.
[0160] As can be seen from FIG. 17C, in this particular amorphous transformer design, the design is configured so that the conductor coils 1002, 1004 support the weight of the amorphous core 40. One possible outcome of allowing the individual amorphous strips comprising the core 40 to move relatively freely, is that in transformer assemblies, where the core is assembled with the conductor coils whereas the core weight is supported upon the top of the conductor coils, the back wall 46 of the core 40 can become compressed thereby decreasing performance of the amorphous ribbon. In order to reduce this compression, epoxy, or other fixative agent can be applied to areas of a first top corner 41 of the core and/or a second top corner 42 of the core so as to support a partial separation of the amorphous strips. The purpose of such a proposed fixative agent is to create a space between the sheets of amorphous ribbon and transfer weight to the inner and outer wraps of the coil. In one preferred arrangement, the epoxy or fixative agent can be applied as highly viscous strips across the cast edge of the amorphous strips with limited penetration between the strips. Alternatively, it can be applied as a thin, easily-absorbed liquid that is readily absorbed between the amorphous sheets in or near the corner areas 41, 42. Alternatively, epoxy or other fixative agent can be applied as strips or other configuration atop a portion of the core leg or legs so as to provide rigidity, and transfer weight of the core legs to the inner wrap to avoid compression of the back wall of the core and thereby achieve enhanced core performance.
[0161] Exemplary embodiments of the present invention have been described. Those skilled in the art will understand, however, that changes and modifications may be made to these embodiments without departing from the true scope and spirit of the present invention, which is defined by the claims.
