GB2105523A

GB2105523A - One-piece core plate for electrical inductive apparatus

Info

Publication number: GB2105523A
Application number: GB08225798A
Authority: GB
Inventors: Peter Niemz; Friedrich Debus
Original assignee: E Blum GmbH and Co
Current assignee: E Blum GmbH and Co
Priority date: 1981-09-09
Filing date: 1982-09-09
Publication date: 1983-03-23
Also published as: SE8205076L; DE3135684A1; FR2512579A1; BE894353A; SE8205076D0; ES515603A0; DK402582A; ES8306548A1

Abstract

A one-piece core plate for a transformer, choke or ballast coil has one or more windows (2, 3). To permit one section (8) of the plate to be introduced into a coil or coil former, a slit (9, 10) extends from the or each window outwardly. To form a definite clearance air gap at the slit, one pair of deformations (11, 12; 13, 14) is formed in the limb (5) of the plate opposite that (4) which is penetrated by the slits, for each window and at positions remote from the slit. <IMAGE>

Description

SPECIFICATION One-piece core plate with at least one window for transformers, choke coils, stabilizers or the like, as well as a method and tool for the production thereof.

The invention relates to a one-piece core plate with at least one window for transformers, choke coils, stabilizers or the like, in which for the introduction by means of one section, e.g. by means of a limb, into a coil a slit is provided which extends outwardly from the window as far as the outer edge of the plate and an air gap is present between the opposed cut edges, which (air gap) is formed by partly producing a permanent deformation in a region remote from the gap and as this has become known by DE-OS 28 24 207.

Moreover, the gap, i.e. a defined interval between the cut edges, may be produced by the fact that the cut edges are first formed by a cut and the interval between the cut edges is (then) enlarged, in that an indentation is formed on a side remote from the slit and a deformation is thereby produced which effects the spreading apart of the opposed cut edges and consequently the air gap is produced that is necessary for the introduction of the plate into a coil. The defined air space can however also be formed in that first a relatively large interval is stamped out between the cut edges and then the relatively wide gap previously formed by stamping is reduced in width by a material forming operation, e.g. by producing an indentation in a cross-sectional region of the core plate opposite the outer edge.It has been proved that, under large series production conditions and over a long period of time, i.e. over a large number of parts, a uniformly good flatness cannot in many cases be attained, the reasons for which are to be looked for inter alia in the fact that the stamping die which is provided for example in the upper part of the tool for producing the air gap produces under the plate to be formed in the lower side of the tool a depression which is prejudicial to the flatness of the plate. This disadvantage cannot be removed even by placing harder material underneath.

Accordingly, the present invention is based on the problem of removing these disadvantages, namely especially to ensure the flatness of the plates to be produced, to increase the life of the tools and to eliminate damage, as well as to be able to produce the plates and the tools simply and economically.

This is achieved according to the invention in core plates of the kind initially referred to in that the permanent deformation is formed both on the upper side and also on the lower side, namely opposite each other. The formation of deformations located opposite each other, e.g. in the form of impressions, corrugations or the like ensures, after this has taken place by means of punches from the upper side and also from the lower side, that a bending in the one direction and consequently the development of warpings is prevented.

According to an additional feature of the invention, it is particularly advantageous if at least two impressions are provided for each gap on the upper side and on the lower side, since in such a case the impressions need be made of only a small size, which moreover largely eliminates the influence of variations in the thickness and in the strength of the sheet metal employed.

The several depressions provided per gap may be arranged in proximity to each other and in the same boundary margin, and hence for example in the longitudinal margin or in the transverse margin, of the window. It may, however, also be advantageous to provide at least one of the deformations in the upper side and also in the lower side on the other boundary margins of the window, and thus on the longitudinal side and on the transverse side.

For the production of core plates according to the present invention a method can prove particularly advantageous according to which the deformations are produced for forming the gap both from the upper side and from the lower side simultaneously and at the same station of the tool. Furthermore, it may be advantageous if also several deformations per gap or window are produced at one and the same station of the tool.

The formation of these deformations for the production of a gap may take place at that station of the tool at which the production of the fixing holes and/or the stamping out of the windows and/or the formation of the slit or gap takes place when the punch is sunk into the bottom die.

The invention also relates to a tool for carrying out the method and for producing one-piece core plates with at least one window, which is characterised in that there is provided both in the upper part and also in the lower part for the formation of a deformation a respective chisel-like stamping die. It may, however, furthermore be advantageous if a punch with at least two chisellike stamping surfaces is provided both in the upper part and also in the lower part for the production of the deformations in the core plate for the formation of a gap.

Irrespective of the construction of the stamp, it may be advantageous if at least the punch provided in one of the parts of the tool, i.e. in the upper part or in the lower part, is adjustable in respect of the extent to which it projects.

Furthermore, it may be advantageous if the tool is so constructed that, at that station at which the deformations are produced, thus in the upper part or in the lower part, or in both, a relief is provided compared with the level of the neighbouring stations.

The invention is explained in greater detail with reference to Figures 1 to 3.

In them: Figure 1 shows a core plate produced according to the invention, Figure 2 shows a section on the line li-lI in Figure 1 on an enlarged scale and Figure 3 shows a section through a tool for the production of core plates according to Figure 1.

The M-shaped one-piece core plate 1 has two windows (2, 3) as well as two yokes (4, 5) and two side limbs (6, 7). A tongue or middle limb (8) extends from one of the yokes (4) in the direction towards the other yoke (5) and intersects the latter, so that air gaps (9, 10) are provided between the cut edges (9a, 9b or 1 0a, 1 Ob). The air gaps (9, 10) are formed by the fact that the cut edges (9a, 9b or 1 ova, lOb) formed in the tool are produced during the severing of the yoke.There is at first no air gap, but on the contrary during the severing a widening out of the material takes place, so that the cut edges are hooked during packing and also when the core plate is introduced via the tongue (8) into a coil. In order to ensure a suitable gap-in the case of plates for transformers a gap (9, 10) which is as small as possible-and the uniformity of the gaps throughout large numbers of parts, there are provided for each of the gaps, i.e. in the regions of the plate adjoining each of the windows (2, 3), a plurality of indentations--in the present embodiment two indentations (11, 12) or (13, 14)-namely in proximity to each other on the transverse side (b) of the window (2, 3).The indentations could, however, be provided instead in the longitudinal side (1) or at least one indentation could be provided in the transverse side and at least one in the longitudinal side.

In Figure 2 it is clear that indentations (1 1, 12) are formed not only from the upper surface (15) but also from the lower surface (16), namely opposite each other and of equal depth. Also indentations (13', 14') are located on the other side opposite the indentations (13, 14).

The air gaps (9, 10) can also, however, be produced, as mentioned initially, in that first relatively wide gaps (9, 10) are stamped out and (then) the gaps are reduced in size by producing deformations of material, e.g. in the form of indentations(11, 11',12,12',13 13',14,14')at the position on the yoke opposite the position now shown, i.e. in the outer side.

Figure 3 shows, as already mentioned, a section through one station of a sequential tool in which the indentations (11,11', 12, 12', 13, 13', 14, 14') are produced. Moreover, punches (18, 19) are provided in the lower part (17) and punches (21, 22) in the upper part 20, which (punches) have respectively two chisel-like stamping surfaces (1 so, 1 8b) or (19a, 19b) and (21 a, 21 b) as well as (22a, 22b) which project from the parts (17, 20) by an amount corresponding to the size of the indentations to be produced (11, 11' to 14, 14'). The punches (21, 22) in the upper part can be adjusted in respect of the extent to which they project by means of a wedge adjustiny device (23, 24). The upper part (20) in this station has, compared with the level (25) indicated by a broken line, of the other stations, a relieved part or a recess (26).

Claims

1. One-piece core plate with at least one window for transformers, choke coils, stabilizers or the like in which, for the introduction of one section into a coil, a slit is provided which extends outwardly from the window as far as the outer edge of the plate and an air gap is present between the opposed cut edges, which (air gap) is formed by partly producing a permanent deformation in a region remote from the gap, characterised in that the permanent deformation (11,11'; 12,12'; 13,13'; 14,14') is formed both on the upper side and on the lower side (15, 16) opposite each other.

2. One-piece core plate according to claim 1, characterised in that at least two impressions (11, 12: 11 12'; 13,14; 13', 14') per gap are provided on the upper side and on the lower side (15, 16).

3. One-piece core plate according to claim 1 or 2, characterised in that the several impressions (11,12 and 11', 12'; 13,14 and 13', 14') provided per gap (9, 10) are arranged in proximity to each other in the same boundary margin (b) of the window (2, 3).

4. One-piece core plate according to claim 1 or 2, characterised in that at least one deformation is provided on the upper side and also on the lower side in the other (1 and b) of the boundary margins of the window (2, 3).

5. Method of producing a one-piece core plate with at least one window, according to at least one of claims 1 to 4, characterised in that the deformationslll, 11'; 12,12' or 13,13'; 14, 1 4') for forming the gap (9 or 10) are produced both from the upper side and also from the lower side (16,17) simultaneously and at the same station.

6. Method according to claim 5, characterised in that the deformations (11,11'; 12,12' or 13, 13'; 14, 14') for forming the gap (9, 10) are produced simultaneously and at the same station of the tool.

7. Method according to one of claims 5 or 6, characterized in that the formation of the several deformations(11, 12; 11', 12' or 13,14; 13,14') for the production of a gap (9 or 10) takes place at that station of the tool at which the production of the fixing holes and/or the stamping out of the windows (2, 3) and/or the formation of the split or gap takes place when the punches are sunk into the bottom die.

8. Tool for carrying out the method according to one of claims 5 to 7 and for producing a onepiece core plate with at least one window according to one of claims 1 to 4, characterised in that there is provided in the upper part and in the lower part (1 7 and 20) for the formation of a deformation (11,11 1'to 14,14') a respective chisel-like stamping die.

9. Tool for carrying out the method according to claims 5 to 7 for producing a one-piece core plate with at least one window, according to one of claims 1 to 7, characterised in that a punch (18, 19; 21, 22) with at least two chisel-like sta mping surfaces ( 1 8a, 1 86; 1 9a, 1 9b; 21 a, 21 b; 22a,22b) is provided both in the upper part and also in the lower part (17 and 20) for the production of the deformations (11,11 to 14, 14') in the core plate for the formation of a gap (9, 10).

10. Tool according to claim 8 or 9, characterised in that at least the punches (21, 22) provided in one of the parts (20) of the tool are adjustable in respect of the extent to which they project.

11. Tool according to one of claims 8 to 10, characterised in that, at the station at which the deformations (11, 11 ' to 14, 14') are produced, a relief (26) compared with the level (25) of the other stations is provided in at least one of the parts, namely in the upper or lower part (17, 20).