DE102013012659B4 - Process and embossing tool for the production of an electrotechnical coil - Google Patents

Abstract

Method for producing an electrotechnical coil (1), in which a semi-finished product in the form of a strip or wire is pre-wound to form a coil (2) with one or more windings (2a, 2b), and the pre-wound coil (2) being placed in a stamping tool (3) inserted and when closing the embossing tool (3) is subjected to an axial pressure acting in the direction of the coil winding axis (A) in such a way that the windings (2a, 2b) of the prewound coil (2) are reshaped to achieve the final coil shape, the embossing tool (3) comprises a plurality of segments (3a, 3b) arranged one above the other in its axial direction (A) and running in a closed manner in its circumferential direction, with the segments (3a, 3b) of the embossing tool (3) first are moved apart in the axial direction (A), the pre-wound coil (2) is then threaded axially into the embossing tool (3) until the individual windings (2a, 2b) of the pre-wound coil (2) each come to rest on a segment (3a, 3b) of the embossing tool (3), with the segments (3a, 3b) then being moved together in the axial direction (A), so that the individual windings (2a, 2b) of the pre-wound coil (2nd ) are formed under pressure between adjacent segments (3a, 3b), and after the segments (3a, 3b) have been moved apart, the finished coil (1) is removed from the embossing tool (3).

Description

The invention relates to a method for producing an electrotechnical coil. According to a second aspect, the invention relates to an embossing tool for producing the final shape of an electrotechnical coil from a pre-wound coil.

In electrical engineering, coils are important components of electrical assemblies or devices. In particular in rotating electromechanical energy converters (electric motors or electric generators), such electrotechnical coils are regularly used in a wide variety of forms.

The electrotechnical coil, which is also simply referred to as a coil in the further description, has a spiral structure, with a conductor loop with one or more windings being wound around a central axis, which is also referred to as the coil winding axis in the further description. Freely selectable parameters when constructing these coils are the number of windings, the cross-sectional dimensions (width and height) of the windings and the distance between the windings and the coil winding axis, which does not have to be constant with increasing winding angle (e.g. upwards or downwards conical, cylindrical, concave or convex winding forms). The shape, viewed in the direction of the coil winding axis, with which the individual windings of the coil are wound around the coil winding axis, can also be adapted to almost any housing shape or other required shape (e.g. coils 1 with essentially rectangular windings 1a, 1b, 1c, ... 1n, see 1 ).

In order to achieve a high level of efficiency, for example in an electric motor, the available winding space must be wound with a high fill factor, i. H. Free spaces between the windings of the coil must be eliminated as far as possible. In the case of conventional coils wound from metallic round wire, the cross section of the winding space is not fully utilized since, due to the circular winding cross section, certain free spaces are inevitably set between the individual windings of the coil. As a result, with round wire, the effectively usable cross-sectional area of the winding space is limited to a theoretical maximum of approx. 78%, which is why rectangular profile wires are increasingly being used, especially with large machines and thick solid wires, whereby filling factors of over 90% can be achieved.

From the U.S. 2005/0 258 704 A1 a method for producing a winding for the stator of an electrical machine is known, in which strands of the winding are pressed into a shape corresponding to the slot before they are placed in the slots of the stator core, thereby facilitating the introduction of the winding into the slots and increasing the slot fill factor becomes. For this purpose, the strands are positioned in a pressing machine in such a way that pressing plates are inserted between the strand sections to be introduced into the groove. These press plates are then moved together by means of an upper and lower press ram, so that the strand sections are pressed flat between the press plates.

A method of manufacturing toroidal coils is disclosed in US Pat DE 462 950 A disclosed. In this procedure, a simple cylindrical coil is inserted between two combs. Then the teeth of one comb are pushed into the tooth gaps of the other comb. During this insertion, every second turn of the cylindrical coil is shifted radially outwards.

At the in 1 In the known coil 1 shown for an electric motor, the challenge now is to deform or bend the flat, rectangular conductor cross-section in a spiral around the coil winding axis A in such a way that the rectangular shape of the individual windings 1a, 1b , 1c, ... 1n, each with four very narrow radii. Forming methods that are used to deform a flat and, for example, rectangular metal strip along the vertical axis include edge bending, flow forming or incremental forming methods. However, all these forming processes suffer from the problem that very small radii, as are regularly required for the coil geometries of today's electric motors (see radii r of the known coil 1 according to 1 ) cannot be formed.

A further geometrical challenge with known coils 1 is that, depending on the winding 1a, 1b, 1c, . . . , 1n of the coil 1, they can have different cross-sectional dimensions (width b and height h of the winding). At the in 2 The known coil 1 of an electric motor shown in cross section and wound around the pole tooth 6 of a stator 7 clearly shows that the cross-sectional dimensions (width b and height h) of the individual windings 1a, 1b, 1c, ..., 1n vary from winding to winding Alter, starting with a wide, flat wrap (in 2 the top, outer winding 1n) continuously changes into a narrow but high winding (in 2 the bottom inner winding 1a). The reason for this in 2 illustrated continuous adjustment of the winding cross-sections Q is is that, on the one hand, the cross-sectional area F of the electrical conductor must be kept at a constant value, independent of the winding, in order to be able to deliver a predefined power or torque for given phase currents, but on the other hand, the geometry of the depression to be filled (groove between radially outwards standing pole teeth 6 of a stator 7) for form-fitting filling (seen in the radial direction Rs of the stator 7) necessarily requires a widening of the individual windings 1a, 1b, 1c, ..., 1n perpendicular to this radial direction _Rs in order to keep the filling factor high.

In order to produce coils 1 with such a variable winding-dependent conductor cross section, the conductor must be preformed in a complex manner in several forming steps before the actual winding process (e.g. by several pairs of squeezing rollers) in order to obtain the required profile of the cross-sectional dimensions b, h. A more reliable and simpler way to produce complex coil geometries is provided by the DE 10 2010 020 897 A1 proposed casting process, which, however, involves a high use of energy and is therefore very expensive.

The object of the invention is therefore to provide a method and an embossing tool for producing an electrotechnical coil, with which coils of the type mentioned can be produced more efficiently than before, with high requirements with regard to the finally desired coil geometry also being able to be met.

With regard to the method, this object is achieved according to the invention by the features of claim 1 .

According to a first aspect of the invention, a method for producing an electrotechnical coil is provided, with a strip-shaped or wire-shaped semi-finished product first being pre-wound to form a coil with one or more windings. The pre-wound coil obtained in this way is then placed in an embossing tool and, when the embossing tool is closed, subjected to axial pressure acting in the direction of the coil winding axis in such a way that the windings of the pre-wound coil are deformed to achieve the final coil shape. The embossing tool comprises a plurality of segments which are arranged one above the other in its axial direction and run in a closed manner in its circumferential direction, with the segments of the embossing tool first being moved apart in the axial direction for forming the pre-wound coil and the pre-wound coil then being threaded axially into the embossing tool until the individual Windings of the pre-wound coil each come to rest on a segment of the embossing tool. The segments of the embossing tool are then moved back together in the axial direction so that the individual windings of the prewound coil are formed under pressure between adjacent segments of the embossing tool, with the finished coil being removed from the embossing tool after the segments have been moved apart.

First, a corresponding strip or wire-shaped semi-finished product, e.g. B. a square material or a round wire, selected, wherein the cross section of the selected semi-finished product should essentially already correspond to the cross section of the windings in the finally desired coil geometry. After the coil has been pre-wound from this semi-finished product, the pre-wound coil is advantageously embossed in a embossing tool as a single and final forming step for producing the final coil geometry.

The pre-winding, for example on a stable pre-winding mandrel, does not represent a technical difficulty, whereby the windings of the pre-wound coil, viewed in the direction of the coil winding axis, should already have a shape (round shape, rectangular shape, trapezoidal shape, etc.) that is as close as possible to the final winding form to be achieved. Advantageously, the final shaping of the coil geometry then takes place in a single shaping step in a stamping tool, in that when the stamping tool is closed all the windings of the prewound coil are converted simultaneously into the desired final winding geometry.

For the simultaneous embossing of all windings of the pre-wound coil using the embossing tool, the latter is made up of several segments. The embossing tool permits at least two operating positions for automated coil production, an open position with the segments moved apart for inserting the pre-wound coil and removing the finished coil, and a closed position with the segments moved together for press-forming the individual coil windings.

According to one embodiment of the method, the windings of the prewound coil are preformed by a radius embossing tool before being placed in the embossing tool. The radius preforming is carried out in such a way that support is first provided above and below a winding of the pre-wound coil, with a stamping die then radially separating the respective winding from the coil winding axis outwardly into an embossing die to form a radius of the coil.

This additional radius preforming step is preferably carried out for coils with windings that are rectangular or otherwise polygonal in shape, viewed in the direction of the coil winding axis (see Fig 1 ) since each winding has a number of very tight corner radii that cannot be reliably prewound by conventional coil winding techniques. The final desired target radii of the windings are achieved in that the individual windings of the pre-wound and pre-formed coil are then subjected to axial pressure in the embossing tool, as already described.

A further embodiment of the method provides for the pre-wound coil to be stretched in the direction of its coil winding axis before it is placed in the embossing tool.

By pulling the coil pre-geometry apart, the necessary free distance between the windings is created, which is necessary for inserting and forming the individual windings in the embossing tool.

According to yet another embodiment of the method, the windings of the pre-wound coil are shaped in the embossing tool in such a way that the cross sections of the individual windings in terms of width and height and/or the angles of the side flanks of the individual windings are converted to their final dimension. In particular, in this embodiment of the method, depending on the winding, different cross sections and/or different angles of the side flanks can be produced.

Despite the use of an extremely inexpensive starting material, the method according to the invention thus allows the production of complex coil geometries (as exemplified in 2 shown) with simple means by a simple embossing process. On the one hand, the cross-sections of all windings of the pre-wound coil are adjusted at once, i.e. simultaneously, by the action of an axial pressure (directed in the direction of the coil winding axis) through this embossing process, and on the other hand, from winding to winding (as in 2 shown) different winding cross sections are formed.

The embossing tool can preferably also be heated in order to hot-form the windings of the prewound coil when the embossing tool is closed.

In the case of large winding cross sections in particular, hot embossing is to be preferred, since significantly larger changes in shape can be achieved here than with cold embossing. Alternatively, instead of heating the tool, it would be possible to heat the workpiece to be formed, ie the pre-wound coil, beforehand.

According to another development of the method, the coil can also be post-processed mechanically after the forming process in the embossing tool, in particular in order to remove burrs from the coil.

A “final coil shape” within the meaning of the present invention is therefore not to be understood as meaning that the coil formed by means of the embossing tool is not subjected to any further processing steps. Rather, this term means that the coil does not require any further forming steps to adapt the coil geometry (in particular the cross-sectional dimensions of the individual windings) after the embossing process.

With regard to the embossing tool, the object mentioned at the outset is achieved according to the invention with an embossing tool having the features of claim 7 .

The embossing tool provided according to a second aspect of the invention for producing the final shape of an electrotechnical coil from a prewound coil comprises a plurality of superimposed in the axial direction of the tool and in a cross section perpendicular to the axial direction of the tool, each adapted to the corresponding cross section of the prewound coil segments designed as approximately rectangular rings that are closed in the circumferential direction of the tool. These segments can be moved apart and together in the axial direction of the tool for inserting and forming the individual windings of the prewound coil.

Due to the multi-segment structure of the embossing tool, all individual windings of the pre-wound coil can be formed simultaneously in a single forming step. In addition, the segments can easily be designed in such a way that different winding cross sections result from embossing from winding to winding (as is the case with the well-known, in 2 illustrated coil is the case).

Since the final winding cross-section is produced in each case in that the respective winding is squeezed between adjacent tool segments a variable design of the segments along the tool axis, a corresponding change in the winding cross sections along the coil axis can also be achieved. In contrast to conventional coil manufacturing methods, it is therefore not necessary to first produce the individual windings with different cross sections in separate forming steps and then to join them together, which is why the embossing tool according to the invention enables a very efficient and therefore cost-effective way of manufacturing complex coil geometries.

According to one embodiment of the embossing tool, the segments are each provided with a recess for accommodating a winding of the prewound coil.

When the embossing tool is moved together, due to these recesses, a closed circumferential cavity is formed between the segments in the circumferential direction of the tool. The dimensions of this cavity correspond exactly to the geometry of the winding to be produced, so that when axial pressure is exerted on the respective winding of the prewound coil, the cavity between the segments is completely filled by the winding material and the winding assumes the geometry of the respective cavity.

Another embodiment relates to an embossing tool in which the segments are divided into at least two sub-segments in the axial direction of the tool, with at least two sub-segments of a segment being offset from one another in the radial direction of the tool, and with this offset in the segment having a groove-shaped recess for receiving one turn of the prewound coil.

Such a sub-segmentation of the individual segments of the embossing tool advantageously means that only one of the at least two sub-segments of a segment is required to support the coil winding in the direction of the coil winding axis. The one or more sub-segments of the segment only delimit the respective recess in the radial direction and do not assume any supporting function in the axial direction, so that they do not constitute an obstacle to the axial threading of the pre-wound coil into the embossing tool.

In order to further simplify the axial threading of the prewound coil into the embossing tool, at least one sub-segment, which is offset further inwards in the radial direction of the tool than at least one further sub-segment of the respective segment, can be moved radially outwards in the segments of the embossing tool.

This cassette-shaped construction of the embossing tool with sub-segments that can be moved radially outwards allows the pre-wound coil to be embossed to be inserted centrically into the segments in the axial direction of the embossing tool without any problems. For this purpose, the sub-segments used during the embossing process for axial support of the individual windings must be moved radially outwards far enough that a through-opening is obtained in the axial direction of the embossing tool within the segments, the dimensions of which are larger than the external dimensions of the pre-wound coil.

To control the material flow, a mandrel running in the axial direction of the tool can be arranged centrally within the segments.

This additional mandrel prevents the winding material from flowing into the interior of the coil, as a result of which mechanical post-processing of the coil that may be necessary to remove burrs on the inside can advantageously be dispensed with.

• 1 die dreidimensionale Ansicht einer erfindungsgemäß hergestellten Spule nach dem Prägen, also in endgültiger Spulenform,
• 2 einen Querschnitt durch eine Motorgeometrie, in welche die in 1 gezeigte Spule eingesetzt ist,
• 3 einen Querschnitt durch ein Radiusprägewerkzeug gemäß der Erfindung, in das die Wicklung einer vorgewickelten Spule eingesetzt ist, und
• 4 einen Querschnitt durch ein Prägewerkzeug gemäß der Erfindung, in das eine zu prägende, vorgewickelte Spule eingesetzt ist.

The prior art and exemplary embodiments of the invention are explained in more detail below with reference to the figures. They each show in partially simplified representations:

• 1 the three-dimensional view of a coil produced according to the invention after embossing, i.e. in the final coil shape,
• 2 a cross section through an engine geometry, in which the in 1 shown coil is inserted,
• 3 a cross-section through a radius stamping tool according to the invention, in which the winding of a pre-wound coil is inserted, and
• 4 a cross section through an embossing tool according to the invention, in which a pre-wound coil to be embossed is inserted.

1 shows the basic structure of an electrotechnical coil 1, which has been produced by the method according to the invention using an embossing tool 3 according to the invention. A wide variety of functions in electrical circuits and electromechanical applications can be assumed by such an electrotechnical coil 1 . In particular, such an electrotechnical coil 1 as in 2 shown, used in electrical engineering as an important functional component of an electric motor.

How out 1 As can be seen, a coil 1 is produced according to the invention with a large number of windings (the individual windings are numbered here and denoted by 1a, 1b, 1c, ..., 1n), the windings spiraling around the coil winding axis A, which is the central axis of the coil 1 corresponds, are arranged.

Depending on the application, the geometry of the coil 1 can be adjusted, in particular the number of windings n, the winding cross-section Q (especially the height h and width b of the electrical conductor wound into the coil 1) and the distance between the windings 1a, 1b, 1c, ... , 1n to the coil winding axis A, which does not have to be constant along the coil height (e.g. in the case of conically shaped coils), represent important geometric parameters that are decisive for the subsequent characteristics of the motor, generator or other electrical assembly.

In the 1 The coil 1 shown has, viewed in the direction of the coil winding axis A, approximately rectangular windings 1a, 1b, 1c, . . . 1n, so that an approximately cuboid coil 1 is obtained. In addition, the conductor wound into a rectangular spiral has a flat, rectangular cross-section Q, which is particularly evident from the sectional view of 2 clearly emerges.

This coil geometry with windings 1a, 1b, 1c, . . 2 to achieve partially illustrated electric motor. This efficiency depends crucially on the fill factor, i.e. on how high the proportion of the electrical conductor is in the available winding space. With conventional coils made of metallic round wire (e.g. made of copper, aluminum or their alloys), the cross-sectional area of the available winding window cannot be fully utilized and the effectively usable area for round wires is theoretically just under 78%. By using a rectangular winding cross section Q, on the other hand, the windings 1a, 1b, 1c, .

In the 1 and 2 Due to its rectangular winding cross section Q and its rectangular coil cross section viewed in the direction of the coil winding axis A, the coil 1 shown has a very high structure density and thus a very high fill factor, which reaches values well above 90%. Despite these clear advantages in efficiency, rectangular coils 1 with rectangular winding cross sections Q, as exemplified in 1 and 2 shown, has not yet been widely used in the field of electrical engineering and so, for example, stator windings of conventional rotating electrical machines are today mostly still formed from round wire coils.

The main reason for this lack of market penetration is that it still causes great production difficulties to deform or bend the conductor with a flat, rectangular conductor cross-section over the vertical axis in order to let it run spirally around the winding axis A. In particular, according to coils 1 for electric motors 1 and 2 , which are designed in the form of a rectangular spiral with a flat, rectangular winding cross-section geometry, represent a very great technical production challenge, because very small corner radii r must be formed here for each winding 1a, 1b, 1c, ..., 1n. Such small radii r as are required for the coil geometries of today's electric motors for reasons of efficiency cannot be formed using conventional forming processes such as edge bending, flow forming or incremental forming processes.

In view of these difficulties, in the DE 10 2010 020 897 A1 suggested that in 1 and 2 produce coil 1 shown by a casting process. In contrast to conventional forming processes, complex coil geometries can also be produced with such a primary forming process. However, in comparison to forming processes, primary shaping processes require a very high level of energy (in the present case for melting the winding material), which is why such primary shaping processes often fall below the economic limit in view of the high energy prices.

The exemplary embodiment of a method according to the invention described below not only allows the production of complex geometries of today's coils 1, but is also extremely advantageous economically because of its few forming production steps.

Depending on the dimension and size of the individual windings 1a, 1b, 1c, ..., 1n in the final coil 1 (e.g. according to 1 ) the selection of a corresponding endless semi-finished product, e.g. B. in the form of a round wire or square material. The cross section of the semi-finished product should correspond to the cross section Q of the later coil windings 1a, 1b, 1c, ..., 1n 1 and 2 come as close as possible to reduce the required degree of deformation.

The selected semi-finished product is then pre-wound (e.g. by means of a high-speed production device) into a coil 2 with a plurality of windings 2a, 2b. The shape, viewed in the direction of the coil winding axis A, with which the individual windings 2a, 2b of the prewound coil 2 have been wound around the coil winding axis A, e.g. B. round shape, rectangular shape, trapezoidal shape, etc., is also brought as close as possible to the final cross-sectional shape to be achieved. In the case of manufacturing a rectangular coil 1, as in 1 shown, the coil 2 is prewound for this purpose in such a way that it has a rounded rectangle as a cross section perpendicular to the coil winding axis A, the radii rv of the corners being formed as small as possible in order to almost correspond to the later rectangular shape.

For better shaping of sharper radii r, the windings 2a of the pre-wound coil 2 are pre-shaped by a radius stamping tool 4 as an additional shaping step after the pre-winding. In 3 this additional forming step performed on the winding 2a of a prewound coil 2 has been illustrated schematically. This figure shows a view in the direction of the coil winding axis A onto a corner area of the winding 2a of the prewound coil 2 inserted into a radius embossing tool 4.

In this corner area, the prewound coil 2 has a radius rv that is still too large to fit in a single, in 4 illustrated embossing process to be able to be transferred to the target radius r by axial pressure application. Accordingly, after the pre-winding and before the final embossing operation, 4 another radius preforming of the pre-wound coil 2. The individual windings 2a of the pre-wound coil 2 are in this case each on both sides in the direction of the coil winding axis A, ie above and below the winding 2a, by in 3 clamping elements, not shown, are supported in order to avoid an undesired axial movement of the winding 2a during the radius stamping process.

After the winding 2a has been fixed axially in this way, an embossing die 4a arranged within the winding 2a is pressed radially outwards from the coil winding axis A against the corner radius rv of the winding 2a of the prewound coil 2, the embossing die 4a except for an embossing die 4b drives. The stamper 4a and the stamping die 4b are each provided on their facing surfaces with a radius r _P which approximates the narrow radius r of the rectangular windings 1a, 1b, 1c, ..., 1n in the final coil form 1 is equivalent to. By pressing the winding 2a of the prewound coil 2 between the embossing punch 4a and the embossing die 4b, this narrow radius r _P is embossed in the corner region of the winding 2a of the prewound coil 2. In order to be able to emboss all corner radii rv of all windings 2a, 2b of the pre-wound coil 2 simultaneously in a single forming step, a multi-segment radius embossing device is preferably provided, which has a radius embossing tool 4 with an embossing die for each winding 2a, 2b and each corner radius rv of the pre-wound coil 2 4a and embossing die 4b according to 3 having.

The embossing force exerted by the embossing die 4a on the prewound coil 2 to be embossed is in 3 marked by a thick arrow F _x,y . For better process management, additional forces can act on the straight sections of the winding 2a of the prewound coil 2 in the direction of their corner radius rv. These additional compressive forces applied to the winding 2a (e.g. by means of a corresponding clamping of the pre-wound coil 2) are in 3 also characterized by thick arrows F _x , F _y and advantageously provide additional compressive stress in the bending radius. In this way, springback of the embossing radius r _P that occurs when the yield point is exceeded can be eliminated or at least reduced.

The required (in 3 Support of the pre-wound semi-finished product in the direction of the coil axis A (not shown for reasons of clarity) can also be provided by the method described below and in 4 Schematically illustrated embossing tool 3 can be achieved, so that radius embossing tool 4 according to 3 and embossing tool 3 according to FIG 4 can also be combined in a universal embossing device. The embossing of the pre-wound coil 2 can thus be realized in a highly efficient manner both in the radial and in the axial direction of the coil one after the other or simultaneously in a single embossing device.

To get the final shape of the pre-wound and using the radius embossing tool 4 after 3 To produce a preformed coil 2, the coil 2 is first stretched in the direction of its coil winding axis A. By pulling apart the pre-wound coil 2, which has been pre-formed in the corner radii, a necessary free distance is produced between the windings 2a, 2b, which is necessary for inserting and forming the coil 2 in the segment-shaped embossing tool 3 according to FIG 4 necessary is.

This embossing tool 3 meets the high geometric requirements of the in 1 and 2 end coil geometry shown in a single, final forming step validly manufactured. On the one hand, these high geometric requirements relate to the narrow corner radii r of the rectangular shaped individual windings 1a, 1b, 1c, ..., 1n, which after the preforming in the radius stamping tool 4 according to 3 in the embossing tool 3 4 now get their final shape. However, the high geometric requirements relate primarily to the dimensions b, h of the winding cross-sections Q, which according to the sectional view 2 change fundamentally in the final coil shape from winding to winding.

In order to ensure a constant current density in the individual coil windings 1a, 1b, 1c, . . . 1n, the surface areas F of the winding cross sections Q of the individual windings 1a, 1b, 1c, 2 constant over the entire coil height. However, the width b of the individual windings increases continuously as the height of the coil 1 increases, so that, in order to maintain a constant surface area F, the height h of the individual windings 1a, 1b, 1c, ..., 1n increases with the height of the coil 1 in the same way dimensions decreases continuously. As a result, the height h and width b of the electrical conductor change depending on the respective winding 1a, 1b, 1c, ..., 1n, with a wide, flat winding (the one in 2 uppermost, outer winding 1n) continuously changes into a narrow but high winding (the one in 2 bottom inner winding 1a).

The reason for such a complex coil end geometry with continuously changing cross-sectional dimensions b, h along the coil winding axis A of the windings 1a, 1b, 1c, ..., 1n is that the windings 1a, 1b, 1c, ..., 1n of the Coil 1 must fill the groove 9 between the radially outwardly projecting pole teeth 6 of the stator 7 as optimally as possible in order to achieve the highest possible filling factor and thus the efficiency of the electric motor. Since this groove 9 to be filled between the pole teeth 6 of the stator 7, viewed in the radial direction Rs of the stator 7, is becoming increasingly wide, the coil windings 1a, 1b, 1c, ..., 1n of the inserted coil 1 , as viewed in the radial direction Rs of the stator 7, can be equally widened to keep the space factor high. The increase in the width b of the coil windings 1a, 1b, 1c, 1a, 1b, 1c, ..., 1n constant.

According to 2 the inward side flank 10 of the individual windings 1a, 1b, 1c, . . . The opposite side flank 8 of the individual windings 1a, 1b, 1c, ..., 1n, which is directed towards the outside of the coil 1, has a corresponding angle of inclination α to the coil winding axis A, with this angle α depending on the motor geometry, in particular on the total number of Coils 1 on the stator 7.

In order to achieve this finally desired coil geometry 2 , In particular the changing width b and height h of the individual windings 1a, 1b, 1c, ..., 1n and the angle α of the side flank 8 of the individual windings 1a, 1b, 1c, ..., 1n to be able to produce reliably , the present invention proposes the pre-wrapped and, if necessary, by means of the radius embossing tool 4 after 3 to subject the preformed coil 2 to a simple embossing process, in which the individual windings 2a, 2b of the prewound/preformed coil 2 are converted into the final winding geometry by the application of axial pressure. The embossing tool 3 used for this embossing process is in 4 shown in the form of a schematically simplified vertical sectional view.

The embossing tool 3 contains a segment for each individual winding of the pre-wound coil 2 to be embossed, with 4 for the sake of clarity, only two segments 3a, 3b and two coil windings 2a, 2b are shown. The segments 3a, 3b are in a (not illustrated) cross section perpendicular to the tool axis A, each adapted to the corresponding cross section of the prewound coil 2, as approximately rectangular rings running closed in the circumferential direction of the tool 3. These approximately rectangular ring segments 3a, 3b are arranged coaxially one above the other.

The embossing process takes place in such a way that first the pre-wound coil 2 is inserted in the axial direction A into the central, approximately rectangular opening of the segments 3a, 3b of the embossing tool 3. The coil 2 is inserted until each of its individual windings 2a, 2b is supported on a segment 3a, 3b of the embossing tool 3. For this purpose, each segment 3a, 3b has a groove-shaped recess 5a, 5b into which the individual windings 2a, 2b of the coil 2 are inserted at the start of the embossing process.

In the exemplary embodiment shown, each segment 3a, 3b is divided into two and in turn consists of two sub-segments 3aa, 3ab, 3ba, 3bb which are arranged coaxially one above the other and are each designed as approximately rectangular rings. The sub-segments 3aa, 3ab, 3ba, 3bb are respectively adapted to the pitch angle of the windings 2a, 2b of the prewound coil 2 with respect to the horizontal inclined. The outer dimensions of the sub-segments 3aa, 3ab, 3ba, 3bb are each flush with one another, whereas the inner dimensions of the two sub-segments 3aa, 3ab, 3ba, 3bb of a segment 3a, 3b are chosen to be different. Due to this difference in the inner dimensions of the sub-segments 3aa, 3ab, 3ba, 3bb, an approximately rectangular circumferential groove 5a, 5b is formed in the segments 3a, 3b, which is delimited radially outwards by the sub-segment 3ab, 3bb with the larger inner dimensions .

The prewound coil 2 is accordingly introduced into the embossing tool 3 in such a way that each individual winding 2a, 2b is inserted into the groove-shaped recess 5a, 5b formed in this way. In 4 the pre-wound coil 2 is introduced into the embossing tool 3 in an axial movement from top to bottom until the windings 2a, 2b of the coil 2 with their underside each rest on the lower sub-segment 3aa, 3ba, which has reduced internal dimensions, of the respective segment 3a , 3b come to the edition.

So that the axial insertion movement is not impeded by the sub-segments 3aa, 3ba serving as a support, these sub-segments 3aa, 3ba can preferably be moved radially outwards. When the sub-segments 3aa, 3ba, which have reduced internal dimensions, are in the radially extended position, the coil 2 can be pushed into the central opening of the embossing tool 3 up to a certain stop position without any obstacles. Only after this stop position has been reached are the sub-segments 3aa, 3ba with the reduced internal dimensions moved from the radially extended position back into the radially retracted position (in 2 shown) position so that the windings 2a, 2b of the pre-wound coil 2 can be placed on these sub-segments 3aa, 3ba.

In 4 the embossing tool 3 is shown in an open operating position, which is assumed when the pre-wound coil 2 is inserted into the embossing tool 3 . The two-part segments 3a, 3b are spaced apart from one another in the axial direction A of the tool 3 in order to be able to accommodate between them the individual windings 2a, 2b, which are also spaced apart from one another due to the stretching of the prewound coil 2. To carry out the embossing process, the embossing tool 3 with the inserted coil 2 to be embossed is brought from the open to a (not shown) closed operating position by the segments 3a, 3b of the embossing tool 3 being moved together in the axial direction A until they stop.

This movement of the segments 3a, 3b together causes the individual windings 2a, 2b of the prewound coil 2 to be deformed. When the embossing tool 3 is closed, the segments 3a, 3b move in opposite directions towards one another in the axial direction A until they rest against one another. The adjacent segments 3a, 3b exert an axial pressure symmetrically from both sides on the winding 2a of the prewound coil 2 arranged between them.

This axial pressure changes the winding cross section Qv with which the coil 2 has already been prewound. When the two segments 3a, 3b come into contact, the winding 2a arranged between them has reached its final winding cross section. This final winding cross-section corresponds to the shape of the cavity between the adjacent segments 3a, 3b when both come into abutment. According to 4 the hollow space that is present when the embossing tool 3 is closed and that determines the cross-sectional geometry of the respective winding 2a, 2b is formed by the peripheral groove-shaped recess 5a, 5b, which is provided in the individual segments 3a, 3b.

If the embossing tool 3 is closed, the material of the winding 2a, 2b completely fills the groove-shaped recess 5a, 5b. The recess 5a, 5b and thus the flow of material in the axial direction A is limited in each case by the sub-segments 3aa, 3ba of the contacting segments 3a, 3b, which have reduced internal dimensions, while in the radial direction R outwards the sub-segments 3ab, which have larger internal dimensions , 3bb serve as a limitation for the material flow. In order to also limit the material flow directed radially inwards during the embossing process, a mandrel running in the axial direction A can be introduced centrally within the segments 3a, 3b and thus in the middle of the coil.

As a result, the winding 2a, 2b of the pre-wound coil 2 is formed into a final cross-section when the embossing tool 3 is closed, which in its trapezoidal shape (ie in height h, in width b and in angle α of the side flank) exactly matches the contour of the respective groove-shaped recess 5a, 5b corresponds. According to the geometric requirements of the final coil shape to be achieved 2 this end cross-section differs from winding to winding. As a result, each groove-shaped recess 5a, 5b is designed differently from segment to segment, which is easily achieved by changing the height and/or the internal dimensions of the sub-segments 3aa, 3ab, 3ba, 3bb installed in the respective segment 3a, 3b can be.

The invention described above enables the production of coils 1 with complex, winding-dependent geometries from a very cheap starting material sold on the market as a mass product (strip or wire-shaped semi-finished product, e.g. sheet metal strips in square shape, square material or even round wire). The coils are manufactured using a forming process, which makes it possible to economically produce the coils 1 (despite their complex geometry) in large numbers.

In the embossing tool 3, the prewound coil 2 is produced all at once by a short embossing stroke, i. H. all the windings 2a, 2b of the coil 2 are formed simultaneously in a single forming step. It is therefore not necessary to initially produce the individual windings 1a, 1b, 1c, . . . The method according to the invention thus permits, on the one hand, very good coil quality (no joints, high surface quality due to the embossing process) and, on the other hand, ensures extremely efficient manufacture of the electrotechnical coil.

Claims (11)

Method for producing an electrotechnical coil (1), in which a semi-finished product in the form of a strip or wire is pre-wound to form a coil (2) with one or more windings (2a, 2b), and the pre-wound coil (2) being placed in a stamping tool (3) inserted and when closing the embossing tool (3) is subjected to an axial pressure acting in the direction of the coil winding axis (A) in such a way that the windings (2a, 2b) of the prewound coil (2) are reshaped to achieve the final coil shape, the embossing tool (3) comprises a plurality of segments (3a, 3b) arranged one above the other in its axial direction (A) and running in a closed manner in its circumferential direction, with the segments (3a, 3b) of the embossing tool (3) first are moved apart in the axial direction (A), the pre-wound coil (2) is then threaded axially into the embossing tool (3) until the individual windings (2a, 2b) of the pre-wound coil (2) each come to rest on a segment (3a, 3b) of the embossing tool (3), with the segments (3a, 3b) then being moved together in the axial direction (A), so that the individual windings (2a, 2b) of the pre-wound coil (2nd ) are formed under pressure between adjacent segments (3a, 3b), and after the segments (3a, 3b) have been moved apart, the finished coil (1) is removed from the embossing tool (3). procedure after claim 1 , characterized in that the windings (2a, 2b) of the prewound coil (2) are preformed by a radius embossing tool (4) before being placed in the embossing tool (3), in that a winding (2a) of the prewound coil ( 2) a support is provided and an embossing punch (4a) presses the respective winding (2a) radially outwards from the coil winding axis (A) into an embossing die (4b) in order to form a radius (r) of the winding (2a). procedure after claim 1 or 2 , characterized in that the pre-wound coil (2) is stretched in the direction of its coil winding axis (A) before it is placed in the embossing tool (3). Method according to at least one of the preceding Claims 1 until 3 , characterized in that the windings (2a, 2b) of the pre-wound coil (2) in the embossing tool (3) are formed such that the cross sections (Q) of the individual windings (1a, 1b, 1c, ..., 1n) with respect Width (b) and height (h) and/or the angle (α) of the side flanks (8) of the individual windings (1a, 1b, 1c, ..., 1n) are converted into their final dimensions, depending in particular on the winding (1a, 1b, 1c, ..., 1n) different cross sections (Q) and / or different angles (α) of the side flanks (8) are generated. Method according to at least one of the preceding Claims 1 until 4 , characterized in that the embossing tool (3) is heated so that the windings (2a, 2b) of the prewound coil (2) are hot-formed when the embossing tool (3) is closed. Method according to at least one of the preceding Claims 1 until 5 , characterized in that after the forming process in the embossing tool (3), the coil (1) is mechanically reworked, in particular to remove burrs from the coil (1). Embossing tool (3) for producing the final shape of an electrotechnical coil (1) from a prewound coil (2), the embossing tool (3) having a plurality of superimposed ones in the axial direction (A) of the tool (3) and in a cross section perpendicular to the Direction (A) of the tool (3) in each case in adaptation to the corresponding cross section of the pre-wound coil (2) as approximately rectangular, in the circumferential direction of the tool (3) running closed segments (3a, 3b), and wherein these segments ( 3a, 3b) for inserting and forming the individual windings (2a, 2b) of the prewound coil (2) in the axial direction Device (A) of the tool (3) can be moved apart and together. embossing tool claim 7 , characterized in that the segments (3a, 3b) are each provided with a recess (5a, 5b) for receiving a winding (2a, 2b) of the prewound coil (2). embossing tool claim 7 or 8th , characterized in that the segments (3a, 3b) are divided into at least two sub-segments (3aa, 3ab, 3ba, 3bb) in the axial direction (A) of the tool (3), at least two sub-segments (3aa, 3ab, 3ba, 3bb) of a segment (3a, 3b) in the radial direction (R) of the tool (3) have an offset (ΔR) to one another, this offset (ΔR) in the segment (3a, 3b) having a groove-shaped recess (5a, 5b) for Recording a winding (2a, 2b) of the pre-wound coil (2). embossing tool claim 9 , characterized in that for the axial threading of the pre-wound coil (2) into the embossing tool (3) in the segments (3a, 3b) of the embossing tool (3) in each case at least one sub-segment (3aa, 3ba) which in the radial direction (R) of the tool (3) is offset further inwards than at least one further sub-segment (3ab, 3bb) of the respective segment (3a, 3b), can be moved radially outwards. Embossing tool according to at least one of the preceding Claims 7 until 10 , characterized in that a mandrel running in the axial direction (A) of the tool (3) is arranged centrally within the segments (3a, 3b).

Images