GB2112673A

GB2112673A - One-piece core plate for a transformer, or the like, and a method and tool for the production thereof

Info

Publication number: GB2112673A
Application number: GB08225801A
Authority: GB
Inventors: Friedrich Debus; Peter Niemz
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: 1983-07-27
Also published as: SE8205075L; ES515602A0; FR2512580A1; BE894354A; SE8205075D0; DE3135687A1; DK402682A; ES8307410A1

Abstract

A one-piece core plate for a transformer, choke or the like 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 an air gap at the slit, at least two deformations (11,12; 13,14) are formed in the plate for each window 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, and 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 first forming the cut edges by a cutting operation and (then) enlarging the distance between the cut edges, in that an indentation is formed on a side remote from the slit and a deformation is thereby produced which effects a spreading apart of the opposed cut edges and the air gap that is necessary for the introduction of the plate into a coil is thereby produced.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 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 larger scale series production conditions, the size of the air gaps cannot in all cases be kept within the necessary narrow limits, which (difficulty) is caused inter alia by the divergence of the thicknesses of the material and also the strengths (thereof) within a batch of plates.

Accordingly, the invention is based on the problem of ensuring the uniformity of the air gap and to provide a method and tool for producing such plates, and consequently to eliminate to a large extent the influence of the variations in material and the divergences in the strength of material as well as the effects (thereof) on the air gaps.

Furthermore, the plates and the tools should be simple and economic to manufacture.

This is achieved according to the invention, in core plates of the kind initially referred to, in that for each air gap in one and the same window at least two deformations are provided. By such means, for example by producing two deformations in the form of impressions, indentations, corrugations or the like, production (of these deformations) can first of all take place with a relatively small depth and/or surface area, whereby, in addition to the relatively small detriment to the lines of force caused by the relatively small deformation of material, a relatively small wear of the tool even over large numbers of parts and also the uniformity of the air spaces is guaranteed, since the influence of the variations in the thickness of material and of the variations in strength is offset by the number of stamped parts for the production of each one of the gaps.

The deformations may be in proximity to each other and in the same boundary margin of the window, thus for example on the transverse side of the window or on the longitudinal side thereof. On the other hand, it may however be advantageous for many applications if the deformations are provided in the other boundary margin, thus for example one deformation in the transverse side and one in the longitudinal side of the margins surrounding the window concerned.

According to a further embodiment according to the invention, the deformations are provided opposite each other both on the upper side and also on the lower side of the plate. By this means the plates are prevented from being able to become warped, e.g. by the stresses that are exerted from one side, i.e. faultless flatness of the plates so produced is attained.

The invention also relates to a method of producing a one-piece core plate with at least one window which is characterised in that the deformations for the formation of one and the same gap are produced simultaneously and at the same station of the tool. If the core plate has a plurality of windows, it is a question for example of a one-piece core plate with a middle limb and two side limbs with windowforming openings provided on each side of the middle limb, in which the middle limb is rigidly connected with one of the yokes and the other of the yokes is intersected, then it may be advantageous to produce the indentations for both of the windows at the same station of the tool and also simultaneously.It is furthermore advantageous if also the deformations which are formed both from the upper side and also from the lower side of the plate are stamped simultaneously and at the same station of the tool.

A development of the method according to the invention is characterised in that the formation of the plurality of deformations for the production of a gap takes place at that station of the tool at which the production of the fixing holes and/or the stamping out of windows and/or the formation of the slits or gaps takes place during the sinking of the punches into the bottom die.

The tool according to the invention for carrying out the method, and for producing one-piece core plates with at least one window is characterised in that a chisel-like stamping die is provided in the upper part and/or in the lower part of the same for producing each deformation. For far the most usual applications a tool is however suitable which is provided, both in the upper part and also in the lower part, for the production of deformations for the formation of a gap, with a plunger having two-or, in case more depressions are necessary for the formation of a gap, correspondingly many-chisel-like stamping surfaces.

It is furthermore advantageous if, in the tool, the stamps provided in at least one of the parts-the upper part or the lower part-are adjustable in respect of the extent to which they project.

It has furthermore proved to be advantageous to construct the tool so that, at the station at which the deformations are produced, and thus in the upper part or in the lower part or in both, a relief compared with the level of the neighbouring stations is provided.

The invention will now be explained in greater detail by way of example with reference to Figs. 1 to 3, in which: Figure 1 shows a core plate produced according to the invention, Figure 2 shows a section on the line ll-ll in Fig. 1 on an enlarged scale and Figure 3 shows a section through a tool for the production of core plates according to Fig.

1.

The N-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 outwardly 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, 9 b and lob). The air gaps (9,10) are formed by the fact that the cut edges 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 will be 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 gap 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 (1 3,14)-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 Fig. 2, it is clear that indentations (11, 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, 1 2', 13, 13', 14, 14') at the position on the yoke opposite the position now shown, i.e. in the outer side.

Fig. 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 (18a, 18b) or(19a, 19b)and(21a, 21 b) as well as (22a, 22b) which project from the parts (17, 20) by an amount corresponding to the size of the indentations (11, 11' to 14, 14') to be produced. 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 adjusting 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 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 at least two deformations (11, 12; 13, 14) are provided in one and the same window (2 and 3) for the air gap (9, 10).

2. One-piece core plate according to claim 1, characterised in that a plurality of deformations(11, 11', 12, 12'; 13, 13'; 14, 14') are provided opposite each other both on the upper side and also on the lower side (15 and 16).

3. One-piece core plate according to claim 1 or 2, characterised in that the deformations (11, 11'; 12, 12'; 13, 13'; 14, 14') are located in proximity to each other in the same boundary margin (b).

4. One-piece core plate according to claim 1 or 2, characterised in that at least one deformation (11, 11'; 13, 13') is provided in one of the boundary margins and at least one deformation (12, 12'; 14, 14') in the other boundary margin (1 and b) of the window (2 and 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 deformations (11; 12 or 1 3; 14) for the formation of one and the same gap (9 or 10) are produced simultaneously and at the same station of the tool.

6. Method according to claim 5, characterised in that the deformations (11, 11', 12 12'; or 13, 13'; 14, 14') for the formation of the gap (9 or 10) are produced simultaneously both from the upper side and also from the lower side (16, 17) and at the same station of the tool.

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

8. Tool for carrying out the method according to one of claims 5 to 7 and for the production of a one-piece core plate with at least one window, according to one of claims 1 to 4, characterised in that a chisel-like stamping die is provided in the upper and/or lower part (17 or 20) for producing each deformation (11, 11' to 14, 14').

9. Tool for carrying out the method according to one of claims 5 to 7 and for the production of 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-shaped die surfaces (18a, 18b; 19a, 19b; 21a, 21 k 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 (1) to form each 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).

1 2. One-piece core plate substantially as described with reference to Figs. 1 and 2.

1 3. A tool for use in forming a one-piece core plate substantially as described with reference to Fig. 3.

14. A method of producing a one-piece core plate substantially as described with reference to the drawings.