FR2504318A1 - Brush unit for multi-segment electric motor commutator - is formed by successive operations on double metal strip and minimises material wastage - Google Patents

Abstract

The process is based on the manipulation and machining of a double strip (B1,B2) of metal. The upper strip, which in formed into the electrical brush surface, is made of a copper-metal alloy and the base strip (B1) is made of steel and acts as a mechanical support. The two strips are welded together along a common central line. The upper strip is folded into a curved channel shape. It has ablong openings machined into it to allow it to be firmly anbedded in an insulating block. Cental sections of the base strip (30,32) are removed to leave end wings (33,34). These are bent through 90 degrees to form a slot which grips the connecting wire. Notches are cut from the ends of the upper brush to allow clamping rings to be fitted. In position, several brush limits are mounted cylindrically around the motor axis. The rings hold them in position.

Description

 The present invention relates to a conductive strip for collectors of rotating electrical machines and its manufacturing process.

 This blade applies to the different types of collectors which can other, either drum collectors, in which the blades are arranged according to the generatrices of a cylinder of revolution, or flat collectors in which the blades are arranged radially on the same plane and converge towards the axis of rotation of the collector.

 Figure t of the accompanying schematic drawing shows a blade for a drum collector) made in; electrically conductive metal such as electrolytic copper. To make a collector such as that shown in cross section in FIG. 2, a certain number of the parts shown in FIG. 1 and called blades, are assembled side by side, the stack forming a cylindrical drum, due to the trapezoidal section of the blades, each of them being electrically insulated from its neighbors by a space 2, constituted either by a special insulating material, or by air. The assembly thus obtained is joined by injecting a synthetic material 3 which is housed, as shown in FIG. 3, which is a sectional view along 3-3 of FIG. 2, between the peripheral assembly q and a central metal core 5, which will allow the assembly of the assembly obtained on the rotor axis 6 of the electric machine. To give it good mechanical strength, the assembly thus molded generally receives several metal rings 7 which are housed in notches 8 formed in the blades of the collector.

These rings are generally two in number, one at each end of the blades, but may be more numerous if the mechanical performance required of the collector requires it.

 The collector shown in the drawing has the role of transmitting the electric current coming from an external source to the winding 9 of the rotor, by means of brushes 10 in contact with the periphery 12 of the collector. The electrical connection between the winding 9 and the collector is provided at each blade by connecting the electrical wires of the winding to the flange 13 of the collector blade, the latter playing the role of interface between the winding and the brushes. This connection is ensured by housing the wires in the slots 14 that comprise the blades of the collector, as shown in particular in FIG. 1.

 It follows from the above description that a traditional collector blade comprises three parts, each having a very distinct function. These three parts emerge more particularly from FIG. 1 and from FIG. 4, which is a side view of a manifold blade.

 The first part 15 of each collector blade is the flange in which a radial slot 14 is made which receives the wires from the winding, making it possible to electrically connect the collector to the winding of the rotor.

 The second part 16 constitutes, once the blades are assembled, the cylindrical track 17 of the collector, on which the electric brushes will rub when the collector rotates. It is the most important part of the collector, which imposes the nature of the material constituting the blade, which is most often pure electrolytic copper treks, or sometimes alloyed with a noble metal such as silver.

 The third part 18 or body of the blade ensures the mechanical resistance of the collector to the stresses of the centrifugal force thanks to its ends 19 and 20, that is to say with the addition of a hoop 22 housed in a notch 23, as shown in FIGS. 1 and 4, either by simply anchoring the blade in the molded material in which case the hook is in the form of a dovetail, as shown by reference 24 in the appended schematic drawing.

 The manifold blades as described above are produced from a metal profile with trapezoidal section which is obtained by stretching as shown in FIG. 5. However, the assembly of the blades imposes a profile whose dimensions of the section transverse must respect very precise dimensional tolerances. Indeed, a difference in the dimensions of the bases of the trapozoSdale section is multiplied by the number of blades constituting the collector, and can lead to a significant variation in the diameter of the latter. A deviation from the basic dimensions of the trapezoidal section also gives the sides of the blades which are not situated in a radial plane and are therefore not oriented towards the axis of rotation of the collector.

 In addition, the production of the flange 15 implies a significant loss of material 25, that is to say in the most massive part of the profile used. Finally, the part 18 of the blade or body must only ensure good mechanical strength of the collector, in particular to withstand the stresses of the centrifugal force to which the collector is subjected in service. However, this part is made of metal with low mechanical resistance, since generally copper, which requires oversizing resulting in an increase in the cost price of the blade.

 The present invention aims to remedy this drawback.

To this end, the conductive strip which it relates to is produced from at least two metal strips integral with 1'Me from the other over only part of their width, one and the other respectively constituting, after shaping, the part comprising the cylindrical or flat track, on the one hand, and the body of the blade on the other hand.

This solution makes it possible to produce a conductive strip from different materials perfectly suited to each function. Thus the part comprising the cylindrical or flat track, and fulfilling the electrical conditions, will be made of electrolytic copper either pure or alloyed with a noble metal such as silver, while the strip corresponding to the body and filling the mechanical conditions such as anchoring in the molded material or mechanical assembly with insulators and flanges in the case of an unmolded manifold, will be made of steel, achieving the double advantage of a lower coat and better mechanical strength . It is thus possible to make a significant saving by replacing a material obtained by stretching ball precision by laminated strips with wider machining tolerances. In any case, the invention will be clearly understood with the aid of the description which follows with reference to the appended schematic drawing representing by way of examples, without limitation, several embodiments of this conductive strip
Figure 6 is a schematic side view of an assembly machine of the strips constituting the blades.

 Figure 7 is a view of a section of two strips intended to form blades in the assembled position.

 Figures 8 to 13 are six views corresponding to six operations of shaping and machining of the blades.

 Figure 14 is a longitudinal sectional view of a blade having reinforcing hoops.

 Figure 15 is a perspective view of an alternative embodiment of the previous blades.

 Figure 16 is a longitudinal sectional view of an alternative embodiment of this blade.

 Figure 17 is a plan view of a manifold.

 Figure 18 is a sectional view along line 18-18 of Figure 17 of this manifold.

 Figures 19 to 23 are five views corresponding to alternative embodiments of manifold blades.

 The manifold blades according to the invention are produced from two metal strips B 1 and B 2 assembled from a welding machine 26 shown in Figure 6.

 The metal strip B 1 is unwound from a roller R 1, while the metal strip B 2 is unwound from a roller R 2.

The assembly is carried out at the level of the machine 26 by electronic bombardment with a beam of electrons.

ble of the two strips B 1 and B 2 assembled is wound on a roller R 3.

 As shown in particular in FIG. 7, the weld bead between the strips B 1 and B 2 is very localized and only corresponds to part of the width thereof.

 As shown in the drawing, the metal strip B 1, which is intended to constitute the electrical part of the blade of the reader, is wider than that of the strip B 2 which is intended to ensure good mechanical strength of the blade.

 The band B 1 is for example made of electrolytic copper, possibly alloyed with a noble metal such as silver, while the band B 2 is made of a material ensuring a mechanical resistance to the blade, such as steel.

 From the assembly of the bands B 1 and B 2, the collector blade is produced by cutting or folding or optional operations on a tool specially designed for this purpose of the type called "tool to be followed" on which several are provided. work stations, each of which performs a specific operation.

 The strip B 2 which is intended to @@@ urer the mechanical tension of the blade @abit a cutting operation, consisting for example in the méxagement of transverse openings 28 in @@@ e that @ e of ar @@ @@ e, @@ 29 of oblong shape, This operation which is carried out @ é @ on @ande B 2 is also dants on the band R 1 which @@ i is superimposed, without that it presents inconveniences in the measurement where it is prefixed to the mive @ ud @@ parts which will be @@@ subsequently deleted.

 As counter @@ figure 10, 11 is @@ quickly proceeded to the shaping of the bende R 2 by porting a part of it relative to the band @@@, which is intended to allow the 'enerage of the @@ d @@@ the molded material.

The given shape which will grease or be compared to a longitudinal median pl @ @ health by @ @, may be that shown in FIG. 10 or @@ present in another form.

The strip B 1 which constitutes the part of the blade is then shaped in the following way:
Two identical plates 30 and 32 are cut on either side of the central part of the strip B 1, which gives a firm flank of T in the siles 33 and 34, as shown in the figure. 11, are intended, in the case of a cylindrical manifold, to constitute the collar. A forming operation is then carried out on the sides 35 of the central part of the strip B 1, which has the aim of giving them an inclination such that they converge towards the axis O of the collector as shown in Figure 12 of the accompanying drawing.

 The two fins 33 and 34 of the strip B 1 are then, as shown in FIG. 13, folded at 900 so as to form the flange, with care for the central slot which the latter has to present.

 There is thus obtained, as shown in FIG. 13, a collector blade ready to be assembled and then molded to give the collector. It should be noted that the strips B 1 and B 2 being assembled continuously, the various manifold blades must be separated from one another according to a determined pitch.

It is interesting to note that such a collector blade is produced at a lower cost, because the different parts of it, namely the electrical part and the mechanical part, are made of suitable materials. the loss of material at the level of the parts 30 and 32, which are removed is very low, and these parts 30 and 32 which are of parallelepiped shape can be reused, either in the electrical industry for the production of lugs for example, or in the mechanical industry for the production of washers
FIG. 14 of the appended schematic drawing represents a variant of this collector blade in which the performance demanded thereof requires the fitting of metal frets 36 which are formed in notches 37 formed in the lower part of the blade, concentrically to axis A of the collector.

 According to another variant, the strip B 2, instead other folded on one side as shown in Figures 10 and 13 above, can be subjected to a double folding as shown in Figure 15. The precise shape of this wing can be variable depending on the intended application.

 This blade can also be used for the production of non-molded collectors, but assembled mechanically by crimping as shown in FIG. 16. In this case, the two flanges 39 and 40 are housed at each end of the lower part of the manifold in which will have been made two notches 42 in the form of a dovetail.

Between each flange and the blade is interposed an insulating rod 43 which achieves the electrical insulation. The flanges 39 and 40 are crimped onto the hub 44 by assembling the manifold blades.

 The manifold blade according to the invention can also be applied to so-called "flat" molded collectors which, in contrast to the "drum" collectors, have their blades forming a flat track instead of another cylindrical one. Such a collector 45 is shown in Figure 17. In this case, the blade does not have fins, but has a radial slot 46 located at its end and at the periphery of the collector. It is this slot which is intended to receive the wires of the winding.

 This blade also has two sides 47 and 48 making an angle between them so as to converge towards the axis of rotation A of the collector.

 Figures 19 to 23 show a number of alternative embodiments of the manifold blade according to the invention.

 In the case shown in FIG. 19, the strip B 1 does not have a rectangular section, but a T-shaped section, so that its central part Q9 is of thickness greater than that of its lateral parts 50.

This increase in section in the center of the blade can also be obtained., As shown in FIG. 20, by welding three bands B 1, B 2 and 52 instead of two bands B 1 and B 2, as described above.

 On certain collectors, the wires of the rotor winding are fixed directly to the body of the manifold blade, where a middle slot 53 will have been made as shown in FIG. 21. In this case, the strip B 1 will have a smaller width which will correspond substantially to the width of the blade track and the sides of which will undergo a forming operation as indicated above so that the edges of the blade converge towards the axis O of the collector.

 In order to reduce the cost of the electron bombardment welding operation, it is possible, as shown in FIG. 22, to weld a strip B 2 to a strip B 1, in the central part of the two strips, then to separate the assembly thus obtained according to a longitudinal median plane, as shown in Figure 23, to obtain two separate blades which will then be machined in the manner described above to give, from each, a number of manifold blades .

 As is apparent from the above, the invention brings a great improvement to the existing technique by providing a collector blade, either cylindrical or planar, which is obtained in an extremely simple manner and at a very competitive coat due to the possibility of each of the parts of the blade in the most suitable material.

 As it goes without saying, the invention is not limited to the sole embodiments of this collector described above, by way of example, it embraces, on the contrary, all the variant embodiments.

Claims (6)

CLAIMS 1. Conductive blade for collectors of rotating electrical machines, characterized in that it is produced from at least two metal strips (D1, B2) integral with one another, over a part of their width only, one and the anantes @@@@@@@@@ t, respectively, after shaping, the par @@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@ case iS - %% i ': - ~ - ------ -M - .-. - from @@@@@@@ e else @@@@@@@@@@@. @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@ térieu @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@ @@@@@@@: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ coné @@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ a @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@ cyl @@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@ parties @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ centrale @@@ unt r @@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@ to each other, to form the collec @@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ bragged therein.  5. Conductive blade according to any one of claims 1 to 4, character @@@. @@@@@@@@@@ that d @@@@ es transverses (28, 29) are méan @ ée. in @@ banie (2 2) constituting the body.  6. Conductive blade according to any one of claims 1 to 5, characterized in that the strip (2) constituting the orp has, after shaping, an asymmetry with respect to the longitudinal median plane of the flange.  7. A method of manufacturing conductive strips according to any one of claims 1 to 6, characterized in that it consists in assembling one to the other two strips (B i, B 2) over part of their width. only, to make transverse cuts (28. 29) in the two superimposed bands, to carry out the shaping of the narrower band intended to drill 1 body, to cut the other band (B 1) in the shape of T , to carry out a forming operation on said strip, in order to give its longitudinal edges an inclination, then in the case of a cylindrical collector, to fold the two wings of the T to 900.  8. Method according to the claim @@ 7, characterized in that the strip (B 2) intended to form the body of the blade undergoes a double folding on the part and @@ cut of its area of attachment to the other strip (@  9. Method according to the claim @@@ 8, characterized in that it consists in relieving the @@@@ able thus obtes @ according to a longitudinal median plane for abto @@ two identical blades,  10. Method according to any one of claims 7 to 9, characterized in that it concists: realize the assembly of the two pincipal bands constituting the blade by electronic bombardment by @@@ @aisceau of electivans.