EP0028494A1 - Method for forming laminations for transformer cores - Google Patents
Method for forming laminations for transformer cores Download PDFInfo
- Publication number
- EP0028494A1 EP0028494A1 EP19800303829 EP80303829A EP0028494A1 EP 0028494 A1 EP0028494 A1 EP 0028494A1 EP 19800303829 EP19800303829 EP 19800303829 EP 80303829 A EP80303829 A EP 80303829A EP 0028494 A1 EP0028494 A1 EP 0028494A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- strip
- pair
- cutting
- cut
- row
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0206—Manufacturing of magnetic cores by mechanical means
- H01F41/0233—Manufacturing of magnetic circuits made from sheets
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
- H01F27/245—Magnetic cores made from sheets, e.g. grain-oriented
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
Description
- This invention relates to laminations for electromagnetic cores particularly for shell-type transformers.
- In such transformers, the core comprises three I spaced apart parallel limbs, around the centre one of which the coil or coils is or are located, and a further pair of parallel limbs magnetically interconnecting the ends of the three parallel limbs. The core is made up of a stack of laminations, and each lamination is in two or more parts thus enabling the laminations to be assembled with the coil or coils. A variety of different shapes are known for the parts of the laminations. For example, each lamination may be made up of an E-shaped part and an I-shaped part which, in the assembled , lamination, interconnects the free ends of the three parallel limbs of the E-shaped part.
- The laminations are generally made from sheet or strip material and an advantage of the aforementioned laminations made of E-shaped and I-shaped parts is that they can be stamped out with substantially no waste of material. The avoidance of waste material is important in view of the high cost of the material employed. Various ways in which the E- and I-shaped lamination parts may be formed are illustrated in UK Patent Nos. 1,466,880 and 1,466,878.
- A further proposal for a two part lamination is illustrated in British Patent Specification No. 1,118,546 (Waasner). This lamination is made up of two parts of identical shape which is such that the line of division between the two parts in the assembled lamination includes a line extending diagonally across the centre one of the three parallel limbs, each part of the lamination comprising first and second limbs which are of generally rectangular shape and are arranged at right angles to each other in the general form of a L and a further limb, of generally triangular shape, which cooperates with the similarly shaped third limb of the other part to form the centre limb in the finished lamination.
- An advantage of this form of lamination is that it is available with resiliently interengageable projections and recesses on the two parts for attaching the two parts together simply by sliding them towards one another in a plane. Thus, in assembling the core, two stacks of lamination parts are formed and are attached to each other in a single operation with the coil assembled around the centre limb, by means of the resiliently interengageable projections and recesses. However,' a disadvantage of this shape of lamination is that it is not possible to manufacture it without substantial waste of material. In practice, 24% to 26% of the material is wasted.
- Laminations made up of two F-shaped parts have previously been proposed in US Patent No. 581,873 (Thomson), issued in 1897, but Thomson failed to disclose any interengageable means for attaching the lamination parts together and to disclose any method of forming the laminations with a minimum of waste.
- One aspect of this invention concerns the problem of minimising waste in the formation of laminations from F-shaped parts, and provides a method of forming F-shaped laminations from a strip of material having parallel edges in which the lines along which the material is cut are such as to form a pattern in which Fs are arranged in pairs, the Fs of each pair being inverted relative to each other with the two parallel limbs of each F embracing the lower one of the two parallel limbs of the other F of that pair, the pairs are arranged in a row extending along the length of the strip with each pair nested with the next pair and the Fs are arranged at an angle to the edges of the material. Two or more rows of Fs may be provided from the same strip. Substantially the only material wasted is at the edges of the strip and thus, the more rows of pairs of Fs which are provided the lower the overall waste. By way of example, if two rows of Fs are provided, the waste may be 8% to 10% whereas if four rows are provided the waste may be 4% to 5%.
- Additionally, the invention provides apparatus for forming F-shaped laminations from a strip of material having parallel edges, comprising first cutting means arranged to cut lines in the strip forming a first F, second cutting means arranged to cut lines in the strip forming a second F which is inverted relative to the first and whose two parallel limbs embrace the lower one of the two parallel limbs of the first F, and means for advancing the strip relative to the first and second cutting means such that these cutting means can cut lines forming a row of pairs of Fs in which each pair is nested with the next pair.
- Another aspect of the invention concerns the problem of providing a multipart lamination which has interengageable means for attaching the parts together and which may be assembled in a simple manner when the parts have orthogonal, parallel sided limbs.
- This aspect of the invention features a two part lamination in which each part comprises a pair of parallel limbs,each said parallel limb having parallel edges, and a further limb at right angles to said parallel with one of the parallel limbs at the end of the further limb and the other intermediate the ends thereof so that each part thereby resembles the letter "F", said lamination parts being provided with interengageable means for attaching them together.
- The interengageable means may comprise projections and recesses arranged to be resiliently interengageable by movement of the parts towards one another in a direction parallel to each of the pairs of parallel limbs.
- The resilient interengagement of the projections and recesses may be achieved by making the projections resiliently flexible and/or by making limbs of the lamination parts resiliently flexible. In a preferred formof the invention, the projections and recesses are interlockable. However, the projections could, alternatively, be a friction fit within the recesses to attach the lamination parts together.
- The invention is described further By way of example with reference to the accompanying drawings in which:-
- Figure 1 is a plan view of a two part lamination;
- Figure 2 shows the lines of cut on a strip of material for forming a plurality of laminations as shown in Figure 1 with a minimum of waste;
- Figure 3 is a view similar to Figure 1 showing an alternative and preferred form of lamination;
- Figure 4 is a view similar to Figure 2 showing the lines of cut for forming the lamination of Figure 3;
- Figure 5 illustrates stamping operations which may be carried out by a progression tool on a strip of material for forming the laminations of Figure 3 with the arrangement of Fs as shown in Figure 4; and
- Figure 6 is an enlarged fragmentry view of a modification of the projections shown in figures 1 and 3.
- The lamination shown in Figure 1 is made up of two
parts part 2a comprises a pair ofparallel limbs 4a and 6a and alimb 8a arranged in the shape of a 'F', thelimb 8a forming the stem of the F and thelimbs 4a and 6a forming the cross members of the F. Thelimbs 4a and 6a are of equal length and their longitudinal edges lOa, 12a, 14a and 16a are all parallel to each other so that thelimbs 4a and 6a are substantially rectangular. Thelimb 4a is provided with aprojection 18a at its free end. The lower corner 20a of the limb 6a is radiussed. Arecess 22a is formed in thelimb 8a near to the end opposite to thelimbs 4a. Thepart 2b is identical to thepart 2a and'includes, therefore, features the same as those described with reference to thepart 2a but identified in the drawing with the same reference numbers but the letter b added instead of the letter a. - The
part 2b is inverted relative to thepart 2a and assembled therewith with theedges 16a and 16b of thelimbs 6a and 6b lying along and in abutment with each other. The two parts are held together by resilient engagement of theprojections 18a and 18b in therecesses 22b and 22a respectively. - In this instance, the projections and recesses are generally rectangular in form and are arranged such that by slight flexing of the
arms limbs - A transformer is assembled using laminations as shown in Figure 1 by forming a stack of
lamination parts 2a and a further stack oflamination parts 2b, then assembling these two stacks with the coil surrounding the limb of the core formed by thelimbs 6a and 6b, the two stacks of laminations simply being held in engagement with each other by the resilient engagement of theprojections 18a and 18b with therecesses 22b and 22a. The provision of the radiussed corners 2Qa and 20b on thelimbs 6a and 6b facilitates the guidance of the leading edge of each of these limbs along the side of 9 the opposite limb when the two parts of the core are assembled with each other. An advantage of this lamination is that tight engagement between theedges 16a and 16b is not essential since flux does not have to cross any gap between these edges. - Referring to Figure 2, the laminations of Figure 1 are formed from a strip of
material 24 which is cut along the lines shown to form tworows F lamination shapes lamination 2a arranged between thelimbs lamination 2b,it thus being seen that theprojections 18a and 18b of thelaminations recesses 30b and 30a respectively in thelimbs 8b and 8a of thelaminations limbs 6a and6b leaves radiusses 32b and 32a at the inside corner between thelimbs - The lines along which the
strip 24 is cut are also such that eachlamination pair edge 34 of thestrip 24 such that thecorners 36a of thelaminations 2a lie on a straight line parallel to theedge 34. Therows narrow margin 38 of saw-tooth shape from each edge of thestrip 24. - With reference to Figure 3,
laminations limbs 8a and 8b instead of on the lower corners of thelimbs limbs recesses 22a and 22b are formed in thelimbs 8a and 8b. Further, the projections 40a and 40b are somewhat of hook shape so as to interlock with the recesses which are of I similar shape. Thus, the projections 40a, 40b are each formed with anose nose limb lamination parts limbs noses noses limbs - It is not essential for the projections 40a, 40b to be located on the
limbs 8a, 8b of the two lamination parts in Figure 3 embodiment and, instead, they may be located on thelimbs projections 18a, 18b of the Figure 1 embodiment. If this is the case, of course, therecesses noses noses - Turning to Figure 6, this shows an alternative shape of projection which may be used in the lamination illustrated in Figure 3 in place of the projections 40a, 40b. This projection, 50, has a
nose 52 with a rounded tip, as before, but in this instance the tip of the nose does not coincide with the outermost end of the projection, which results in the hook shape of the projection in the Figure 3 embodiment, but is disposed half way between the foot of the projection and its outermost end. This strengthens the projection and, at the same time, facilitates assembly of the two lamination parts together. - As shown in Figure 4, the
strip 24 is cut in a manner similar to that shown in Figure 2 for producing the laminations of Figure 3 with a minimum of waste. It will be noted that therecesses limbs 8a and 8b of the laminations of Figure 3 arise from the formation of the projections 40a and 40b and have no functional significance. - The
recesses strip 24 by a progression tool (not shown) , whose operations are illustrated in Figure 5. In Figure 5, thestrip 24 is advanced step wise from right to left by a distance x so that each successive portion of the strip is moved intermittently to each of ten successive zones or stations A to J of the tool. At zone A holes 60 are punched at the edges of the strip for registration purposes as the strip moves through the zones. It will be noted that theholes 60 are staggered relative to each other at the two edges of the strip and this is because of the angle arrangement of the Fs to be cut. No cutting takes place at zone B. At zone C twoapertures 62 and two apertures 64 are punched at spaced positions on a line at a slight angle to a line transverse to the strip. Theapertures 62 will formrecesses recesses - At zone D the shaded area 66 is blanked from the strip thus forming one F-shaped lamination part. No cutting takes place at zone E. At zone F the shaded
portion 68 is blanked from the strip thus forming a further lamination part. - No cutting takes place at zone G or zone I, but at zones H and J the shaded
parts - It should be understood that once the cutting process is operating, the punching or blanking operations taking place at zones A, C, D, F, H and J all take place simultaneously.
- A progression tool for carrying out the operations described with reference to Figure 5 can be constructed by conventional techniques, and therefore need not be described in detail. It is,however, to be understood that the invention also resides in a tool, or other apparatus for carrying out the method described with reference to Figure 5.
Claims (19)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB7938069 | 1979-11-02 | ||
GB7938069 | 1979-11-02 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0028494A1 true EP0028494A1 (en) | 1981-05-13 |
EP0028494B1 EP0028494B1 (en) | 1984-06-20 |
Family
ID=10508947
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19800303829 Expired EP0028494B1 (en) | 1979-11-02 | 1980-10-28 | Method for forming laminations for transformer cores |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0028494B1 (en) |
DE (1) | DE3068319D1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0175662A1 (en) * | 1984-08-24 | 1986-03-26 | Kanthal AB | Method of manufacturing loop-formed metal foil elements |
EP0353029A2 (en) * | 1988-07-27 | 1990-01-31 | Linton And Hirst Limited | Improvements in laminations |
WO1990007782A1 (en) * | 1988-12-23 | 1990-07-12 | Linton & Hirst Limited | Packs of laminations and method and apparatus for forming them |
GB2221354B (en) * | 1988-07-27 | 1993-05-12 | Linton & Hirst Ltd | Improvements in laminations |
ES2157832A1 (en) * | 1999-09-24 | 2001-08-16 | Ventura Ind | Procedure for die-cutting sheets making up magnetic nuclei |
Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1345786A (en) * | 1915-10-14 | 1920-07-06 | Gen Electric | Art of making cores for electrical apparatus |
US3181402A (en) * | 1963-04-03 | 1965-05-04 | David J Kuck | Method of forming f-shaped and l-shaped laminations for shell-type core |
US3201731A (en) * | 1962-11-27 | 1965-08-17 | Electro Netic Steel Inc | Transformer core and lamination therefor |
US3491437A (en) * | 1968-05-06 | 1970-01-27 | Allegheny Ludlum Steel | Scrapless method of stamping e laminations |
DE1929566A1 (en) * | 1968-06-27 | 1970-06-18 | Idec Izumi Corp | Transformer core and process for its manufacture |
US3587020A (en) * | 1969-07-01 | 1971-06-22 | Waasner B | Two-part core sheet for transformers |
FR2070783A1 (en) * | 1969-12-09 | 1971-09-17 | Zumtobel Walter | |
FR2106423A1 (en) * | 1970-09-10 | 1972-05-05 | Friedland Ltd V & E | |
FR2125402A1 (en) * | 1971-02-13 | 1972-09-29 | Siemens Ag | |
FR2202348A1 (en) * | 1972-10-10 | 1974-05-03 | Huyghe Ets | |
FR2367337A1 (en) * | 1976-10-11 | 1978-05-05 | Beresford Joseph | CORE MADE OF MAGNETICALLY PERMEABLE MATERIAL, ESPECIALLY FOR CIRCUIT IMPEDANCE BALLAST AND PROCESS FOR ITS MANUFACTURING |
GB1543567A (en) * | 1976-04-02 | 1979-04-04 | Linton & Hirst Ltd | Manufacture of laminations |
-
1980
- 1980-10-28 EP EP19800303829 patent/EP0028494B1/en not_active Expired
- 1980-10-28 DE DE8080303829T patent/DE3068319D1/en not_active Expired
Patent Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1345786A (en) * | 1915-10-14 | 1920-07-06 | Gen Electric | Art of making cores for electrical apparatus |
US3201731A (en) * | 1962-11-27 | 1965-08-17 | Electro Netic Steel Inc | Transformer core and lamination therefor |
US3181402A (en) * | 1963-04-03 | 1965-05-04 | David J Kuck | Method of forming f-shaped and l-shaped laminations for shell-type core |
US3491437A (en) * | 1968-05-06 | 1970-01-27 | Allegheny Ludlum Steel | Scrapless method of stamping e laminations |
DE1929566A1 (en) * | 1968-06-27 | 1970-06-18 | Idec Izumi Corp | Transformer core and process for its manufacture |
US3587020A (en) * | 1969-07-01 | 1971-06-22 | Waasner B | Two-part core sheet for transformers |
FR2070783A1 (en) * | 1969-12-09 | 1971-09-17 | Zumtobel Walter | |
FR2106423A1 (en) * | 1970-09-10 | 1972-05-05 | Friedland Ltd V & E | |
FR2125402A1 (en) * | 1971-02-13 | 1972-09-29 | Siemens Ag | |
FR2202348A1 (en) * | 1972-10-10 | 1974-05-03 | Huyghe Ets | |
GB1543567A (en) * | 1976-04-02 | 1979-04-04 | Linton & Hirst Ltd | Manufacture of laminations |
FR2367337A1 (en) * | 1976-10-11 | 1978-05-05 | Beresford Joseph | CORE MADE OF MAGNETICALLY PERMEABLE MATERIAL, ESPECIALLY FOR CIRCUIT IMPEDANCE BALLAST AND PROCESS FOR ITS MANUFACTURING |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0175662A1 (en) * | 1984-08-24 | 1986-03-26 | Kanthal AB | Method of manufacturing loop-formed metal foil elements |
EP0353029A2 (en) * | 1988-07-27 | 1990-01-31 | Linton And Hirst Limited | Improvements in laminations |
GB2222030A (en) * | 1988-07-27 | 1990-02-21 | Linton & Hirst Ltd | Laminations for electromagnetic cores |
EP0353029A3 (en) * | 1988-07-27 | 1990-05-23 | Linton And Hirst Limited | Improvements in laminations |
US5047745A (en) * | 1988-07-27 | 1991-09-10 | Linton And Hirst Limited | Laminations |
GB2222030B (en) * | 1988-07-27 | 1993-04-28 | Linton & Hirst Ltd | Improvements in laminations |
GB2221354B (en) * | 1988-07-27 | 1993-05-12 | Linton & Hirst Ltd | Improvements in laminations |
WO1990007782A1 (en) * | 1988-12-23 | 1990-07-12 | Linton & Hirst Limited | Packs of laminations and method and apparatus for forming them |
US5406243A (en) * | 1988-12-23 | 1995-04-11 | Linton & Hirst Limited | Packs of laminations and method and apparatus for forming them |
ES2157832A1 (en) * | 1999-09-24 | 2001-08-16 | Ventura Ind | Procedure for die-cutting sheets making up magnetic nuclei |
Also Published As
Publication number | Publication date |
---|---|
DE3068319D1 (en) | 1984-07-26 |
EP0028494B1 (en) | 1984-06-20 |
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