EP0350855B1 - Commutator and process for manufacturing same - Google Patents

Description

The invention relates to a commutator for electrical machines, the segments of which form at least one seat for a prestressed reinforcement ring which is concentric with the longitudinal axis of the commutator, and to a method for producing such a commutator.

With commutator machines, there is often a desire to reduce the size with the same power by increasing the speed or to increase the power with the same size. The prerequisite for this is that the commutator allows a correspondingly high dynamic load. Commutators in which the segment body is held together only by the insulating press material are inexpensive. However, their dynamic resilience is low. But even commutators in which the segment body is provided with at least one reinforcement ring that is stress-free in the dynamic and thermally unloaded state have only a slightly greater dynamic usability, since the reinforcement rings only have a portion of the pressure relieving the press material when the segment body expands under the centrifugal force can absorb dynamic stress.

For higher dynamic loads, commutators with pretensioned, i.e. already in the dynamically and thermally unloaded state a tensioned reinforcement rings are used. However, such commutators cause higher manufacturing costs. In addition, the smaller the dimensions of a commutator, the more difficult it is to handle during production. In addition, in the case of small dimensions, due to the dimensionally dependent, smaller elastic clamping paths of the reinforcement rings, increased part precision is necessary, since even small deviations in the inner diameter of the reinforcement rings and / or in the diameter of the ring seat lead to considerable differences in tension in the reinforcement rings. This also results in an increasing share of costs as the commutator diameter decreases. This means that commutators with prestressed reinforcement rings for the electrical machines of small to medium size, which are produced in large quantities, are relatively expensive and are therefore generally out of the question for reasons of price.

The invention is therefore based on the object of providing a commutator with pretensioned reinforcing rings which has a significantly higher dynamic and thermal strength than the known pressurized commutators, but is nevertheless inexpensive even with small dimensions, and thus also an increase in performance in the area of small to medium-sized electrical machines allowed by increasing the speed.

This task is solved by a commutator with the features of claim 1.

The plastic pre-shaping of the segment parts forming the seat for the reinforcement ring in the radial direction outwards causes the seat to continue to expand and thus also the expansion of the reinforcement ring, from which the prestressing results. The reinforcement ring can therefore be tension-free on the Seat be applied before its expansion, which results in a significant reduction in manufacturing costs. But the expansion process can also be carried out inexpensively for any size of commutator. In addition, the seat can easily be expanded to such an extent that the reinforcement ring not only experiences an elastic expansion, but also a plastic diameter increase. Therefore, even with relatively large tolerances of the diameter of the seat, the inner diameter of the reinforcement ring can also be dimensioned with relatively large tolerances before it is widened, so that each reinforcement ring can be applied to a seat with a play required for easy handling. The commutator according to the invention can therefore be rationally produced not only for larger, but especially also for small to medium-sized electrical machines manufactured in large quantities, since there is no additional cost share for difficult handling and for increased dimensional accuracy of the individual parts compared to the known press commutators, whose segment body is provided with one or more tension-free reinforcement rings.

The space between the segments can be at least partially filled with press material, as is the case with the known press commutators. However, in the case of the commutator according to the invention, as in the case of commutators of the arch pressure design, the molding material and the segments are under an arch pressure.

The design according to the invention also offers advantages in the field of vault pressure commutators with insulating lamellae and shrink rings or prestressed reinforcing rings arranged between the segments. The known vaulted pressure commutators are characterized above all by an excellent operating behavior of their brush running surface, which results in low heating of the commutator, high operational reliability, less maintenance and a longer service life. The manufacturing effort the known vaulted pressure commutators is, however, considerably higher than that of the known ring-reinforced press commutators. So far, commutators of the arch pressure type have only been used in larger electrical machines where the higher costs are justified due to their area of application.

The advantageous operating behavior of the brush tread in vaulted pressure commutators stems from the fact that a very high pressure and therefore a correspondingly high surface pressure of the segments and the insulating lamellae lying between them is built up via the prestressed rings in the vault of the commutator, as a result of which individual segments migrate even when the segments are full Centrifugal stress is avoided with certainty.

The prerequisite for this is that the commutator has absolutely elastic behavior in all operating states. To achieve this, it is necessary to reduce the diameter of the segment body during the manufacture of the commutator, e.g. B. by pressing into a thick-walled socket that it is formed with plastic deformation of the insulating lamellae before the reinforcing rings are applied to the seats provided for them. Is the reduction in diameter of the segment body much larger than the span of the reinforcement rings and the pressure built up in the vault so high that the reinforcement rings are biased after ejecting the segment body from the bushing so that the vault pressure required for a given operating load builds up in the segment body , it is sufficient to slide the reinforcement rings onto the seats provided for them. However, since the segment body is formed by plastic deformation of the insulating lamellae, the reduction in diameter achieved in the elastic region is significantly smaller than the overall reduction in diameter of the segment body. The size of the reduction in diameter caused in the elastic region becomes determined mainly by the number and strength of the portion of the circumference of the segment body resulting from the insulating lamellae, since the insulating lamellae are relatively soft spring elements compared to the segments made of copper. This means that with a decreasing division, ie in the case of a segment body with a small number of insulating lamellae and segments, the elastic clamping path decreases. In addition, as a result of the physical properties of the insulating lamellae, which usually consist of Micanit, the arch pressure decreases disproportionately to the increase in diameter of the segment body required for the prestressing of the reinforcing rings. For these reasons, it is only possible for commutators with higher parts, which do not require a very high arch pressure to absorb the centrifugal force, to slide the reinforcement rings onto the seat with reduced diameter without tension.

In order to be able to produce commutators of the arch pressure type for high dynamic loads and / or with a low pitch, the thermal expansion of the so-called shrink rings made of steel had to be used up to now. In order to be able to heat such shrink rings quickly and efficiently, the heating had to be done inductively, which means that, in addition to difficult handling when applying the heated shrink ring to its seat, an expensive manufacturing device is also required. The cost of the known vaulted pressure commutators was therefore usually too high for small to medium-sized electrical machines.

If, on the other hand, the seat of each reinforcement ring is plastically expanded according to a known reduction in diameter of the segment body, then it is sufficient to push the reinforcement rings onto the seat in the unheated state. The design according to the invention therefore makes it possible to replace vaulted pressure commutators with shrink rings by more economical vaulted pressure commutators in which the reinforcing rings can be applied without heating.

The design according to the invention makes it possible in a simple manner to produce commutators with prestressed reinforcing rings, the segments of which are spaced in their outer region by separate spacer strips or by spacers molded onto them, which are only removed after the segment body has been pressed out with a molding material embedding them or by overturning the commutator be eliminated.

Since segment bodies constructed in this way permit only a very small reduction in diameter within their elastic range, it is not possible to reduce their diameter so much for the purpose of attaching a reinforcement ring to a seat on the segment body that a high clamping path required for prestressing the reinforcement ring is achieved becomes. However, this is not disturbing for the commutator according to the invention, since the pretensioning of the reinforcement rings is independent of the elastic behavior of the segment body.

Because of this, the design according to the invention also enables the use of one-piece segment bodies which are produced from a profiled tube piece, a profiled strip section or by extrusion.

Since, in the commutator according to the invention, the segment body is not held together by anchoring the segments in the insulating molding material, the anchoring means are not molded onto the segments. This is of great advantage particularly in the case of extruded segment bodies.

It would of course also be possible to apply a reinforcement ring to its seat in the expanded state and then plastically expand the seat.

In a preferred embodiment of the commutator according to the invention, the inner circumferential surface of the segment body bears against the press material filling the space between it and the outer circumferential surface of a hub or shaft or against an insulating or insulated hub or shaft. Because a warm deformation the brush tread, ie a deviation of the brush tread from the cylindrical shape under thermal load can be prevented by pressing the segments in the radial direction on the hub or shaft, the hub or shaft is advantageously biased in the radial direction by the segments and reinforcing rings. Advantageously, this pretension is achieved by shrinking the armored segment body onto the hub or shaft or by pressing pressed material into the space between the hub or shaft on the one hand and the inner surface of the segment body on the other hand and thereby expanding the armored segment body.

It is also advantageous to design the seats for the reinforcement rings according to claim 9. When the commutator is subjected to the highest dynamic stress, the seat then forms a cylindrical surface, as a result of which the reinforcement ring arranged on it experiences uniform stress. This would not be the case if the seat defined a cylindrical surface when the commutator was stationary, since it would then take on a conical shape when subjected to dynamic loads.

The invention is also based on the object of specifying a method according to which the commutator according to the invention is simple to manufacture. This object is achieved by a method having the features of claim 1.

Advantageous further developments and refinements of this method are the subject of claims 12 to 23.

Fig. 1

einen unvollsständig dargestellten Längsschnitt nach der Linie I-I der Fig. 2 des Segmentkörpers eines ersten Ausführungsbeispiels vor dem Aufweiten der Sitze für die Armierungsringe,

Fig. 2

eine unvollständig dargestellte Stirnansicht des Segmentkörpers des ersten Ausführungsbeispiels vor dem Entfernen der Abstandhalter zwischen den Segmenten,

Fig. 3

einen unvollständig dargestellten Längsschnitt des ersten Ausführungsbeispiels im ausgepreßten Zustand,

Fig. 4

einen unvollständig dargestellten Längsschnitt eines Werkzeuges zum Aufweiten der die Sitze bildenden Materialpartien des ersten Ausführungsbeispiels,

Fig. 5

einen unvollständig dargestellten Längsschnitt des Segmentkörpers eines zweiten Ausführungsbeispiels vor dem Aufweiten der Sitze,

Fig. 6

einen unvollständig dargestellten Längsschnitt des zweiten Ausführungsbeispiel im ausgepreßten Zustand,

Fig. 7

einen unvollständig dargestellten Längsschnitt nach der Linie VII-VII der Fig. 8 des Segmentkörpers eines dritten Ausführungsbeispiels,

Fig. 8

eine unvollständig dargestellte Stirnansicht des Segmentkörpers des dritten Ausführungsbeispiels,

Fig. 9

einen Schnitt entsprechend Fig. 7 einer Abwandlung des dritten Ausführungsbeispiels,

Fig. 10

einen unvollständig dargestellten Längsschnitt des dritten Ausführungsbeispiels im fertigen Zustand,

Fig. 11

eine unvollständig dargestellte Stirnansicht des Segmentkörpers eines vierten Ausführungsbeispiels,

Fig. 12

einen Schnitt nach der Linie XII-XII der Fig. 11,

Fig. 13

eine unvollständig dargestellte Ansicht der anderen Stirnseite des Segmentkörpers des vierten Ausführungsbeispiels,

Fig. 14

eine unvollständig dargestellte Stirnansicht des vierten Ausführungsbeispiels im fertigen Zustand,

Fig. 15

einen Schnitt nach der Linie XV-XV der Fig. 14,

Fig. 16

einen Schnitt nach der Linie XVI-XVI der Fig. 14,

Fig. 17

eine unvollständig dargestellte Ansicht der einen Stirnseite des Segmentkörpers eines fünften Ausführungsbeispiels,

Fig. 18

eine unvollständig dargestellte Ansicht der anderen Stirnseite des Segmentkörpers des fünften Ausführungsbeispiels,

Fig. 19

einen Schnitt nach der Linie XIX-XIX der Fig. 18,

Fig. 20

einen unvollständig dargestellten Längsschnitt des fünften Ausführungsbeispiels im fertigen Zustand,

Fig. 21

einen unvollständig dargestellten Längsschnitt eines Werkzeuges zum Aufweiten der Sitze für die Armierungsringe des fünften Ausführungsbeispiels,

Fig. 22

einen unvollständig dargestellten Längsschnitt eines sechsten Ausführungsbeispiels,

Fig. 23

eine Seitenansicht eines Segmentes des sechsten Ausführungsbeispiels im montagefertigen Zustand,

Fig. 24

einen unvollständig dargestellten Längsschnitt einer Vorrichtung zum Aufweiten der Sitze des sechsten Ausführungsbeispiels,

Fig. 25

eine perspektivisch dargestellte Ansicht eines Profilbandstückes, an dem die einzelenen Arbeitsschritte zur Herstellung von Segmenten für das zweite Ausführungsbeispiel ersichtlich sind.

The invention is explained in detail below on the basis of exemplary embodiments illustrated in the drawing. Show it

Fig. 1

3 shows an incompletely illustrated longitudinal section along line II of FIG. 2 of the segment body of a first exemplary embodiment before the seats for the reinforcing rings are widened,

Fig. 2

3 shows an incompletely illustrated end view of the segment body of the first exemplary embodiment before the removal of the spacers between the segments,

Fig. 3

an incompletely shown longitudinal section of the first embodiment in the pressed state,

Fig. 4

FIG. 2 shows an incompletely illustrated longitudinal section of a tool for expanding the material parts of the first exemplary embodiment that form the seats, FIG.

Fig. 5

3 shows an incompletely illustrated longitudinal section of the segment body of a second exemplary embodiment before the seats are widened,

Fig. 6

an incomplete longitudinal section of the second embodiment in the pressed state,

Fig. 7

8 shows an incompletely illustrated longitudinal section along line VII-VII of FIG. 8 of the segment body of a third exemplary embodiment,

Fig. 8

3 shows an incompletely illustrated end view of the segment body of the third exemplary embodiment,

Fig. 9

7 shows a section corresponding to FIG. 7 of a modification of the third exemplary embodiment,

Fig. 10

an incompletely shown longitudinal section of the third embodiment in the finished state,

Fig. 11

3 shows an incompletely illustrated end view of the segment body of a fourth exemplary embodiment,

Fig. 12

11 shows a section along the line XII-XII in FIG. 11,

Fig. 13

FIG. 2 shows an incompletely illustrated view of the other end face of the segment body of the fourth exemplary embodiment,

Fig. 14

3 shows an incompletely illustrated end view of the fourth exemplary embodiment in the finished state,

Fig. 15

a section along the line XV-XV of Fig. 14,

Fig. 16

a section along the line XVI-XVI of Fig. 14,

Fig. 17

FIG. 2 shows an incompletely illustrated view of one end face of the segment body of a fifth exemplary embodiment,

Fig. 18

FIG. 2 shows an incompletely illustrated view of the other end face of the segment body of the fifth exemplary embodiment,

Fig. 19

18 shows a section along the line XIX-XIX of FIG. 18,

Fig. 20

an incompletely shown longitudinal section of the fifth embodiment in the finished state,

Fig. 21

an incomplete longitudinal section of a tool for expanding the seats for the reinforcement rings of the fifth embodiment,

Fig. 22

3 shows a longitudinal section of a sixth exemplary embodiment, which is not fully shown,

Fig. 23

2 shows a side view of a segment of the sixth exemplary embodiment in the ready-to-install state,

Fig. 24

FIG. 2 shows an incompletely illustrated longitudinal section of a device for expanding the seats of the sixth exemplary embodiment,

Fig. 25

a perspective view of a profile strip piece, on which the individual steps for the production of segments for the second embodiment can be seen.

In order to produce a commutator designated as a whole by 1, a hollow cylindrical segment body 3 is composed of segments 2 of the same design, consisting of copper or another suitable metal. On each segment 2, as the left half of FIG. 2 shows, in the edge zone adjoining the outer circumferential surface of the segment body 3, a narrow spacer bar 4, which has the same thickness as the desired distance, extends over the entire axial length of the segment body 3 is selected between the segments 2. Instead of this integrally formed on the segments 2 spacer bars can also, as shown in the right half of Fig. 2, between the segments 2 each use a separate spacer bar 4 ', the thickness of which is chosen as that of the spacer bars 4. In the assembled state of the segment body 3, the spacer strips 4 or 4 'lie on the side surface of the adjacent segment 2.

The segment body 3 is provided on both ends with an annular groove 5 running concentrically to its longitudinal axis. The two material grooves 6 delimiting these ring grooves 5 against the longitudinal axis of the segment body 3 each form a seat for a reinforcement ring 7. The axial length of the material parts 6 is slightly greater than the axial length of the reinforcement ring 7 to be accommodated, but is significantly smaller than the axial length of the the annular groove 5 outwardly delimiting material portion of the segments 2. Furthermore, the width of the annular grooves 5 is greater than the thickness of the reinforcing rings 7 measured in the radial direction, so that a space is present between them and the outer boundary surface of the annular grooves 5.

As shown in Fig. 2, the segments 2 from their inner surface of the segment body 3 forming end radially outwards to the height of the annular grooves 5 into both sides, by an extension 8 'of the outside by the spacer strips 4 or 4' defined slots 8 received.

The reinforcement rings 7, which are insulated steel rings, but instead of which glass fiber reinforced plastic rings could also be used, can be pushed onto their seats with play. After this has been done, the material parts 6 of, two mutually movable mandrels 9 (see Fig. 4), which are pressed from the two end faces into the segment body 3, so far radially outward that the plastic expansion of the ring seat Reinforcement rings receive the desired tension. During this widening, as shown in FIG. 4, the segment body 3 is located in a thick-walled bushing 10, which prevents the outer diameter of the segment body 3 from increasing during the widening process. The seats interrupted in the circumferential direction by the slots 8 for the two reinforcement rings 7 have, after the plastic deformation of the material parts 6, a diameter which becomes somewhat larger towards their open end, as shown in FIG. 3. Furthermore, due to the plastic deformation of the material parts 6, the inside diameter of the segment body 3 is somewhat larger in the area of the material parts 6 than in the middle section lying between them.

Thereafter, the segment body 3 and a steel hub 11 in the form of a cylindrical bush, the outer diameter of which is slightly smaller than the inner diameter of the segment body 3, are placed in a tool in which the space between the outer surface of the hub 11 and the inner surface of the segment body 3, the free spaces between adjacent segments, the still free spaces of the annular grooves 5 and the areas of the segment body 3 with pressed material that are set back in the axial direction relative to the two end faces 12 can be filled. Finally, after the molding material 12 has hardened, the spacer strips 4 'are removed or the segment body 3 is overturned until the spacer strips 4 are completely removed. The segment body 3 is then under a vault pressure generated by the prestressing of the reinforcement rings 7, which presses the segments 2 against the molding material 12 filling the slots 8.

The exemplary embodiment shown in FIGS. 5 and 6 differs from that of FIGS. 1 to 3 only in that the material parts 106 of the segments 102 initially protrude radially inward beyond the central section, as shown in FIG. 5. This protrusion is chosen so large that the required expansion of the reinforcement rings 107, which is partially plastic as with the reinforcement rings 7, is achieved when the inner surface of the material portions 106 facing the longitudinal axis is aligned with the inner surface of the central section of the segments 102 after the expansion process. In the exemplary embodiment, the distance between the inside of the material parts 106 from the longitudinal axis of the segment body 103 to the free end increases slightly, since two mandrels (not shown) have been used for the expansion, which taper slightly towards their free end.

In this exemplary embodiment too, after the reinforcement rings 107 have been prestressed by widening their seats, a hub 111 is inserted concentrically into the segment body 103 and press material 112 is introduced into the intermediate spaces. After it has cooled, the spacer strips 104 are removed by unscrewing.

The segments 202, from which the segment body 203 of the exemplary embodiment shown in FIGS. 7 to 10 is composed, differ from the segments 102 only in that no spacer elements corresponding to the spacer strips 104 are attached to them are molded. This is because an insulating lamella 204 made of micanite is inserted between the segments. The seat formed by the material parts 206 for the two reinforcement rings 207 can be cylindrical before the plastic deformation of the material parts 206, as shown in FIG. 7 and is also the case with the segments 102. However, as shown in FIG. 9, the segments 202 can also be designed in such a way that they initially form a seat which tapers conically towards their free end, which additionally facilitates the application of the reinforcement rings. It is advantageous to provide the seat widening in such a way that when the commutator is at rest, the seat has an increasing diameter toward the free end of the material parts 206 forming it. If the resulting angle, which the surface of the material parts 206 forming the seat encloses with the longitudinal axis, is chosen such that the seat assumes a cylindrical shape when the segments are subjected to maximum centrifugal force, then a uniform and thus optimal stress loading of the reinforcement rings is achieved with this load . In the case of the commutator shown in FIG. 10, which is to be provided with a hub 211 and pressed out with molding material 212, the diameter of the seat for the reinforcing rings 207 and also their diameter toward the adjacent end face of the commutator increases somewhat in the idle state.

In the exemplary embodiment according to FIGS. 7 to 10, the segment body 203 is pressed into a thick-walled bushing before the application of the reinforcement rings 207 for the purpose of forming, ie reducing the diameter while plastically deforming the insulating lamellas 204. Here, an initially excessive arch pressure is reached. The seats for the reinforcement rings 207 are expanded in this socket. If the segment body 203 is now ejected from the bushing, the excessive arch pressure is reduced to almost the normal value while the tension in the reinforcement rings is increased at the same time. Of the Normal value is reached when, finally, the segment body 203 has been shrunk onto a hub 211 'provided with a thin insulating layer 211, the hub 211 receiving a radial prestress.

Such a pre-tensioning of the hub could also be achieved by pressing molding material between the hub and the inner surface of the heated segment body with high pressure, whereby the segment body 203 can be widened until it rests against the inner wall of the press bushing receiving it.

Even in the case of the shrinking of the segment body 203 onto the hub 211, as shown in FIG. 10, the annular space existing due to the axial recessing of the segments 206 and the reinforcement rings 207 as well as the part of the ring grooves not filled by the reinforcement rings 207 and the free spaces between adjacent segments filled with molding material 212.

In the production of the exemplary embodiment shown in FIGS. 11 to 16, it is assumed that there is a one-piece segment body 303 which has been produced by extrusion. Since this is a so-called flat commutator, the brush running surface formed by the segments 302 lies in a radial plane. As further shown in FIG. 12, all segments 302 are initially still connected to one another by a narrow web 304. These webs lie on the side of the segments 302 forming the brush running surface. A connecting ring 304 'which is concentric with the longitudinal axis is formed on this front side to further strengthen the connection between the segments 302. A leg 306 running parallel to the longitudinal axis of the commutator adjoins the radially inner end section of the segments 302. These legs 306, which define a hollow cylindrical part which projects beyond the rear side of the segments 302, represent the material parts which form the seat for a reinforcing ring 307 to be plastically expanded. The legs 306 therefore protrude inward over part of their length the inward end face of segments 302 as shown in FIG. 12. After the plastic expansion of the seat, the inside of the legs 306 is aligned with the inside of the segments 302, as can be seen from FIG. 16.

After the reinforcement ring 307 has been widened, the spaces between the segments 302 and the annular space between a hub 311 and the segments 302 and the leg 306 are filled with molding material 312. In addition, as shown in FIGS. 15 and 16, the reinforcement ring 307 is covered with the molding material 312. Only when the molding material 312 has hardened, the connecting ring 304 'and the webs 304 are turned off. Each segment 302 is then provided with recesses 313 in its outer edge zone for the connection of one winding end.

The commutator shown in FIGS. 17 to 21 also has an extruded segment body 403. However, of the two legs of the segments 402 which run approximately at right angles to one another, the leg lying parallel to the longitudinal axis of the commutator forms the brush running surface, while the leg which projects radially outwards serves as the connection for a winding end. As in the exemplary embodiment according to FIGS. 11 to 16, the extrusion of the segment body 403 is also unproblematic here since no anchoring elements have to be molded onto the segments 402. The segments 402 are only at the end carrying the leg for the solder connection with an open end, which is delimited to the longitudinal axis of the segment body by a material portion 406 to form a first seat and at the other end of the leg forming the brush running surface with an axial end over this tread protruding material portion 406 ', which projects radially inwards and serves to form a second seat. After pushing a reinforcement ring 407 onto the two seats, the material portions 406 and 406 'which delimit them towards the commutator axis are plastically deformed in the radial direction towards the outside. During this deformation, the segment body 403 is covered by a thick-walled bush 401 supported from the outside, as shown in FIG. 21. The mandrel 409 used for the expansion, as also shown in FIG. 21, has two sections with different diameters, so that both seat expansions can be carried out in a single operation. After the two reinforcement rings 407 have been prestressed, a hub 411 is inserted into the segment body 403 and the space between it and the segment body 403 is filled with molding material 412. The pressed material also covers, as shown in Fig. 20, the reinforcing rings 407 and the parts of the material 406, 406 'carrying them completely. Finally, the legs of the segments 402 serving for connection are provided with recesses 415 for the winding ends to be connected, and the segment body 403 is turned over to remove the webs 404 connecting the segments 402.

22 and 23 show, it is also possible to provide the segment body 503 with a seat for a reinforcing ring 507 forming ring grooves 505 'which do not open like the ring groove 505 towards the end face, but only towards the longitudinal axis of the commutator is. 24, all parts of the material 506 of the segments 502, which each form one of the seats, can then be plastically deformed in a single operation by means of a mandrel 509 in the radial direction to such an extent that the reinforcing ring 507 receives the desired tension . The commutator is then finished using one of the methods described above, for example by filling the annular grooves 505 and 505 'and the space between the segment body 503 and a hub 511 with molding material 512.

How the segments for a segment body composed of individual segments, for example the segment body 103, are produced inexpensively can be seen from FIG. 25. A profile strip 116, the profile of which is selected to be the same as the cross-sectional profile of the segments 102 to be produced, is first of all exposed with a T-like punch-out to expose the material parts 106 117 provided. The two arms of the punched-out 117, which extend in the longitudinal direction of the profile band 116, have a width that decreases transversely to the longitudinal extent of the profile band 116 toward their common central section. In a second operation, the material parts 106 are plastically deformed so far in the transverse direction of the profile band 116 by means of a tool to be inserted into the punched-out 117 that the width of the punched-out 117 measured in the transverse direction of the profiled band 116 'is constant over its entire extent in the longitudinal direction of the profiled band 116 is. The surface of the material parts 106 which later forms the seat for one of the reinforcing rings 107 is therefore now parallel to the surface of the segment 102 which will later form part of the brush tread. Finally, the segment 102 is separated from the profiled strip 116 in the middle of the punched-out area 117 '.

Claims (24)

1. Commutators for electrical machines, segments of which form at least one enlarged seat for a prestressed protection ring which is concentric with a longitudinal axis of said commutators, wherein only a material section (6; 106; 206; 306; 406; 406′; 506) of segments (2; 102; 202; 302; 402; 502), which border a said seat outwards from a longitudinal axis of commutators, are plastically deformed in a radial direction outwards.
2. Commutator in accordance with claim 1, wherein each of radially enlarged seats, which are formed by a plastically deformed material section (6; 106; 206; 306; 406; 406′; 506) of segments (2; 102; 202; 302; 402; 502) has interruptions running towards a periphery because of intermediate spaces between adjacent segments.
3. Commutator in accordance with either claim 1 or claim 2, wherein intermediate spaces between segments (2; 102; 202; 302; 402; 502) are at least partly filled with pressed material (12; 112; 212; 312; 412; 512).
4. Commutator in accordance with either claim 1 or claim 2, wherein insulating lamellae (204) are disposed between segments (202).
5. Commutator in accordance with any one of claims 1 to 4, wherein an inside casing surface of a hollow body formed by segments (2, 102; 202; 302; 402; 502) lies on a pressed material (12; 112; 212; 312; 412; 512) which fills a core member (11; 111; 211; 311; 411; 511) or a shaft of an intermediate space between a said hollow body and an outer casing surface, or it lies on an insulating or insulated core member (211) or a shaft.
6. Commutator in accordance with any one of claims 1 to 5, wherein a core member (211) or a shaft is prestressed in a radial direction by means of segments (202) and a protection ring (207).
7. Commutator in accordance with any one of claims 1 to 6, wherein segments (302; 402) are separated sections of a body moulded by extrusion.
8. Commutator in accordance with any one of claims 1 to 7, wherein segments (2; 102; 202) are set back, radially, at least by as much as the height of a seat for a protection ring (7; 107; 207) in relation to an inner bordering surface, in a direction towards a periphery, on one or both sides in the direction of a reduction of their thickness.
9. Commutator in accordance with any one of 1 to 8, wherein a surface, of plastically deformed material sections (6; 106; 206) of a seat, which border, in a direction away from a longitudinal axis of a said commutator, on a protection ring (7; 107; 207), encloses, with a said longitudinal axis of a said commutator, a pointed angle produced by an enlargement of a radial separation from a said longitudinal axis of a said commutator, away from a free end of a said surface, the size of a said angle being at least approximately the same as an elastic deformation of material sections (6; 106; 206) arising at the time of a highest chosen functional loading of a said commutator.
10. Commutator in accordance with any one of claims 1 to 9, wherein an inside boundary surface, of material sections (6; 106; 206) which form a seat, which faces a longitudinal axis of a said commutator, at least runs almost parallel to a longitudinal axis of a said commutator.
11. Process for producing a commutator in accordance with claim 1, in which a segment with at least one seat for a protection ring is produced and a said protection ring is prestressed, wherein, after application of a protection ring onto its seat, the latter is enlarged by supporting segments from the outside inwards and material sections forming a said seat, involving plastic deformation, are moved radially outwards.
12. Process in accordance with claim 11, wherein an enlargement of each seat present is realized in a resulting area of a plastic enlargement of a protection ring disposed on it.
13. Process in accordance with either claim 11 or 12, wherein a segment body, for providing support from the outside inwards, is set in a thick-walled bushing which preferably has at least almost no play.
14. Process in accordance with any one of claims 1 to 13, wherein a radial enlargement of a seat occurs by forcing in at least one expansion pin into a segment body in an axial direction.
15. Process in accordance with claim 14, wherein a second enlargement pin is inserted against a first enlargement pin in a segment body in an axial direction.
16. Process in accordance with either claim 14 or claim 15, wherein at least two seats are enlarged, separated from each other in an axial direction, by means of an enlargement pin.
17. Process in accordance with any one of claims 11 to 16, wherein, after expansion of each seat present and a protection ring disposed on it, pressed material is inserted between segments.
18. Process in accordance with claim 17, wherein a segment body is composed of segments between which spacing members are disposed, preferably between outer areas of said segments, which are removed with pressed material after a said segment body has been forced out.
19. Process in accordance with claim 17, wherein a segment body is composed of segments which, in their outer area, have spacing members formed on them on one or both sides and a said segment body is twisted off until there has been complete removal of spacing elements, after a segment body has been forced out with pressed material.
20. Process in accordance with 17, wherein a segment body is formed by extrusion, with removal of connection members with space segments, and connection members are removed after forcing out of a segment body with pressed material.
21. Process in accordance with any one of claims 18 to 20, wherein a segment body, after expansion of each seat present, is heated and is enlarged in a bushing which takes up a said segment body or shaft by forcing pressed material between a said core body or shaft, on one side and an inside casing surface of a segment body on another side, until said pressed material lies on a said bushing which takes it up.
22. Process in accordance with any one of claims 11 to 16, wherein a segment body is composed of segments and insulating lamellae disposed between these and is forced into a thickened bushing with reduction of its diameter to the extent of plastic deformation of insulating lamellae, and then each protection ring provided is pushed onto a seat associated with it and then radial expansion of each seat present and of each protection ring carried by it occurs.
23. Process in accordance with any one of claims 11 to 22, wherein a segment body is pressed onto a core member of shaft after enlargement of each seat present.
24. Process in accordance with any one of claims 11 to 23, wherein material sections of segments, to be deformed, in the case of deformation from a position in which a surface forming a seat runs parallel to a longitudinal axis of a commutator, in relation to another part of a segment, or its separation thins in a direction away from its free end, are moved into a position in which a separation of a surface forming a seat increases away from a said longitudinal axis of a said commutator towards a free end.

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