US3251120A - Method of making a commutator - Google Patents

Description

May.: 17, 1966 L. REISNECKER METHOD OF MAKING A COMMUTATOR Filed Feb. 12, 1962 United States Patent 3,251,120 METHOD OF MAKING A COMMUTATOR Ludwig Reisnecker, Stuttgart-Rotating, Germany, assignor to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Feb. 12, 1962, Ser. N 172,435

' 5 Claims. (Cl; 29-155.54)

' commutator.

One of the objects of the present invention is to provide a commutator manufacturing process which is exceedingly simple and exceedingly inexpensive, as compared to known commutator manufacturing processes.

Another object of the present invention is to provide a process of the above type according to whichthe raw material from which the commutator is made is exceedingly inexpensive.

It is also an object of the present invention to provide a commutator of the above type which has portions to which armature leads may be very conveniently connected.

Also, it is an object of the present invention to provide a process in which a minimum amount of finishing is required during the last stages of the process.

With the above objects in view the invention includes, in a process for manufacturing a commutator in part from an electrically conductive band having an inner face which in the finished commutator is directed toward the commutator axis and an outer face which in the finished commutator is directed away from this axis and having a flange extending along a side edge of the band and projecting only from the outer face thereof, the steps of pressing two series of tranverse grooves into this band, one series from the inner toward the outer face thereof so as to define elongated segments connected to each other only by bridging portions located at the outer face of the band. and at the bases of the grooves, respectively, and the other series of grooves being respectively aligned with the first series of grooves and extending into the above-mentioned flange up to the outer face of the band, so that each segment is substantially L-shaped and has a relatively long leg extending transversely across the band and a relatively short" leg extending substantially perpendicularly with respect to the band. A plurality of these L-shaped segments, which are still connected by the above bridging portions, are rolled into the shape of a cylinder with the relatively short legs of the-segments directed away from the cylinder axis, and then all of the segments are embedded in a cylindrical body ofelectrieally non-conductive material which fills the above-mentioned first series of grooves and which is surrounded by the cylindrical row of segments. Then the above-mentioned bridging portions are removed so as to leavethe segments separated from each other and supported only by the electrically non-conductive material, and the above-mentioned relatively short legs of the sements are adapted to have armature leads connected thereto.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary perspective illustration of an electrically conductive band used for making the segments of the commutator of the invention, this band being shown in FIG. 1 partially in the configuration it segments, while they are still connected to each other,

are rolled into the shape of a cylinder; and

FIG. 4 is a partly sectional, perspective illustration of the finished commutator of the invention.

Referring to FIGS. 1 and 2, there is shown therein an elongated band 10 of an electrically conductive material such as copper. The upper face of the band 10, as viewed in FIG. 1, forms the inner face which is directed toward the axis of the commutator when the latter is finished, and the lower face of the band 10, as viewed in FIG. 1, forms the outer face thereof which is directed away from the axis of the finished commutator. As is apparent from FIGS. 1 and 2, the band 10 is, in accordance with the invention, pressed with suitable dies so as to have formed therein two series of transverse grooves. The one series of grooves extends fromthe inner (upper as viewed in FIG. 1) face of the band 10 to the outer face thereof so as toseparate the band into elongated segments which are connected to each other by the bridging portions 11 located at the outer face of the band 10 at the bases of the first series of grooves, respectively, and the second series of grooves is formed in a flange of the band 10, this second series of grooves being respectively aligned with the first series of grooves and cooperating therewith to provide each segment with a relatively long leg 10" and a relatively short leg 10', the relatively long leg extending across the band 10 and the relatively short leg extending substantially perpendicularly with respect to the band. This band 10 is of L-shaped cross-section before it is acted upon so as to be formed with the structure shown in FIGS. 1 and 2, so that the original band 10 has along one side edge a flange which extends only from the outer face of the band, which is the lower face thereof as viewed in FIG. 1. The grooves which extend into this flange also extend up to the outer face of the band 10, as is apparent from FIG. 2, so that in this way these pressing operations serve to form the two series of grooves which define the L-shaped segments 10', 10" which are interconnected at this time only by the bridging portions 11 of the'band. The two series of grooves may be formed simultaneously in the band by pressing on the latter with suitable dies which simultaneously act from both sides of the band to give it the configuration indicated in FIGS. 1 and 2.

Curved holding claws 12 are raised from those faces of the segments which are directed away from the relatively short legs 10' thereof, these curved holding claws being formed by any suitable cutting tools which cut into the several segments longitudinally of their relatively long legs 10' so as to raise from each segment a pair of curved holding claws 12, as indicated in FIG. 1.

With the band 10 treated as described above and as shown in FIGS. 1 and 2, the operator selects a number of segments 10, 10 equal to the desired number of segments in the finished commutator, and this number of segments is separated from the band and is rolled into the cylindrical shape shown in FIG. 3, and it will be noted that when the series of segments are rolled into this shape the relatively short legs 10' thereof are directed away from the cylinder axis, and of course the holding claws 12 are directed toward the cylinder axis. It should be noted that before the selected number of segments are rolled into the cylindrical shape shown in FIG. 3, a part of each bridging portion 11 extending from the left edge Patented May 17, 1966 commutator to the shaft of the armature.

the regions thereof which include the relatively short legs and FIG. 3 clearly shows only the remaining portions of the bridging portions 11 interconnecting the several segments at their relatively long'legs 10'.

The assembly of FIG. 3 is then embedded, in a known way and in a suitable mold, in a body 13 (FIG. 4) of electrically non-conductive material, and it will be noted that the holding claws 12 serve to anchor the segments in the body of material 13, this body of electrically nonconductive material filling the spaces between the segments, these spaces being formed by the above-mentioned grooves. The remaining bridging portions 11 are then machined away from the segments in a suitable machine tool or the like so that in this way the remainder of each bridging portion 11 is removed and the segments are now entirely unconnected from each other and are supported only by the body 13 of electrically non-conductive material. The cylindrical body 13 surrounds and engages an inner steel tube 14 which facilitates connection of the The individual shorter legs 10' of the several commutator segments, after the commutator is finished, are formed with slots, by suitable saws, for example, and these slots are adapted to each receive two or more wires of the armature winding, these armature leads being soldered, for example, to the several commutator segments.

Thus, with the process of the invention there is provided a commutator which during its manufacture includes a series of segments connected to each other and rolled into the shape of a cylinder, and the segments of the commutator of the invention each has a substantially L-shaped configuration formed, in accordance with the present invention, from the cross-sectional configuration of the original band 10' which is worked upon according to the invention. This particular configuration makes it very convenient to provide in the shorter leg 10' of each segment a slot adapted to receive the leads of the armature. Up to the present time the commutator segments were formed from fiat, unprofiled bands. By providing the commutator of the invention from a band 10 which is of L-shaped cross-section, the leg 10 provides additional area, as compared to conventional commutator segments, capable of being used in those machines where more than two armature leads are required to be connected to each segment.

Of course, it is within the scope of the invention to provide a band 10 which in its original configuration is substantially U-shaped so as to have a pair of flanges respectively extending from the opposite side edges of the band, since such a construction is particularly suited for relatively small commutators which when provided with a pair of such flanges are far more capable of withstanding the stresses resulting from the pressing operations, and in the case of such small commutators when the bridging portions 11 are machined away the additional flange is also machined away, this latter additional flange being provided only in order to provide such a relatively small commutator with sufficient strength to withstand the forces to which it is subject during the manufacture of the commutator.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of commutators differing from the types described above.

While the invention has been illustrated and described as embodied in commutators and processes for manufacturing commutators, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a process for manufacturing a commutator in part from an electrically conductive band having an inner face which in the finished commutator is directed toward the commutator axis and an outer face which in the finished commutator is directed away from said axis and having a flange extending along a side edge of the band and projecting only from said outer face thereof, the steps of pressing two series of transverse grooves from opposite sides into said band, one series from said inner toward said outer face thereof to define elongated segments connected to each other by bridging portions located at the outer face of the band and at the bases of the grooves, respectively, and the other series being respectively aligned with said first series of grooves and extending into said flange up to said outer face of said band, so that eachsegment is substantially L-shaped and has a relatively long leg extending across the band and a relatively short leg extending substantially perpendicularly to the band; rolling a plurality of the L-shaped segments, connected by said bridging portions, into the shape of a cylinder with said relatively short legs directed away from the cylinder axis; embedding said segments in a cylindrical body of non-conductive material which fills said first, series of grooves and which is surrounded by the cylindrical roll of segments; and removing said bridging portions so as to other and connected together only by said non-conductive material, said shorter legs of said segments being adapted to have armature leads connected thereto.

2. In a process for manufacturing a commutator in part from an electrically conductive band having an inner face which in the finished commutator is directed toward the commutator axis and an outer face which in the finished commutator is directed away from said axis and having a flange extending along a side edge of the band and projecting only from said outer face thereof, the steps of pressing two series of transverse grooves from opposite sides into said band, one series from said inner toward said outer face thereof to define elongated segments connected to each other by bridging portions located at the outer face of the band and at the bases of the grooves, respectively, and the other series being respectively aligned with said first series of grooves and extending into saidflange up to said outer face of said band, so that each segment is substantially L=shaped and has a relatively long leg extending across the band and a relatively short leg extending substantially perpendicularly to the band; removing from the band a part of each bridging portion extending from said side edge of the band inwardly beyond'said relatively short legs of said segments, so that the segments are separated from each other in the region of said relatively short legs thereof; rolling a plurality of L-shaped segment-s, connected by said bridging portion, into the shape of a cylinder with said relatively short legs directed away from the cylinder axis; embedding said segments in a cylindrical body of elec trically non-conductive material which fills said first series of grooves and which is surrounded by the cylindrical roll of segments; and removing the remainder of said bridging portions so as to leave said segments separated from each other and supported only by said non-conductive material, said relatively short legs of said segments being adapted to have armature leads connected thereto.

3. In a process for'manufacturing a'commutator in part from an electrically conductive band having an inner face which in the finished commutator is directed toward leave said segments separated from each the commutator axis and an outer face which in the finished commutator is directed away from said axis and having a flange extending along a side edge of the band and projecting only from said outer face thereof, the steps of pressing two series of transverse grooves from opposite sides into said band, one series from said inner toward said outer face thereof to define elongated segments connected to each other by bridging portions located at the outer face of the band and at the bases of the grooves, respectively, and the other series being respectively aligned with said first series of grooves and extending into said flange up to said outer face of said band, so that each segment is substantially L-shaped and has a relatively long leg extending across the band and a relatively short leg extending substantially perpendicularly to the band; raising a holding claw from that face of each segment which is directed away from said relatively short leg thereof; rolling a plurality of the L-shaped segments, connected by said bridging portions, into the shape of a cylinder with said relatively short legs'of said segments directed away from the cylinder axis; embedding said segments and said holding claws thereof in a cylindrical body of electrically non-conductive material which fills said first series of grooves and which is surrounded by the cylindrical row of segments; and removing said bridging portions so as to leave said segments separated from each other and supported only by said electrically non-conductive material, said relatively short legs of said segments being adapted to have armature leads connected thereto.

4. In a process for manufacturing a commutator in part from an electrically conductive band having an inner face which in the finished commutator is directed toward the commutator axis and an outer face which in the finished commutator is directed away from said axis and having a flange extending along a side edge of the band and projecting only from said outer face thereof, the steps of simultaneously pressing two series of transverse grooves from opposite sides into said band, one series from said inner toward said outer face thereof to define elongated segments connected to each other by bridging portions located at the outer face of the band and at the bases of the groove-s, respectively, and the other series being respectively aligned with said first series of grooves and extending into said flange up to said outer face of said band, so that each segment is substantially L-shaped and has a relatively long leg extending across the band and a relatively short leg extending substantially perpendicularly to the band; removing from the band a part of each bridging portion which extends from said side edge of the band inwardly beyond said relatively short legs of said segments; raisin-g from each of said segments, at a face thereof which is directed away from said relatively short leg thereof, a curved holding claw; rolling a plurality of the L-shaped segments, connected by the remainder of said bridging portions, into the shape of a cylinder with said relatively short legs directed away from the cylinder axis; embedding said segments in a cylindrical body of electrically non-conductive material which fills said first series of grooves and which receives said holding claws, said cylindrical body of electrically non-conductive material being surrounded by the cylindrical row of segments; and removing the remainder of said bridging portions so as to leave said L-shaped segments separated from each other and connected together only by said electrically non-conductive material, said relatively short legs of said segments being adapted to have armature leads connected thereto.

5. In a process for manufacturing a commutator, the steps of first forming a band of L-shaped cross section from electrically conductive material, said band having an inner face which in the finished commutator is directed toward the commutator axis and an outer face which in the finished commutator is directed away from said axis and having a flange extending along one side edge of the band and projecting only from said outer face thereof; simultaneously pressing two series of transverse grooves from opposite sides into said band of L-sha-ped cross section, one series from said inner toward said outer face thereof to define elongated segments connected to each other by bridging portions located at the outer face of the band and at the bases of the grooves, respectively, and the other series being respectively aligned with said first series of grooves and extending into said flange up to said outer face of said band, so that each segment is substantially L-shaped and has a relatively long leg extending across the band and a relatively short leg substantially perpendicular of the band; rolling a plurality of the L- shaped segments, connected by said bridging portions, into the shape of a cylinder with said relatively short legs directed away from the cylinder axis; embedding said segments in a cylindrical body of non-conductive material which fills said first series of grooves and which is surrounded by the cylindrical roll of segments; and removing said bridging portions so as to leave said segments separated from each other and connected together only by said non-conductive material, said shorter legs of said segments being adapted to have armature leads connected thereto.

References Cited by the Examiner UNITED STATES PATENTS 2,634,495 4/1953 Callsen et al 29 1 55.54 2,953,698 9/1960 Gianotto 310 23.5

FOREIGN PATENTS 816,033 7/1959 Great Britain.

JOHN F. CAMPBELL, Primary Examiner.

MILTON O. HIRSHFIELD, WHITMORE A. WILTZ,

R. W. CHURCH, Assistant Examiners.

Claims (1)

1. IN A PROCESS FOR MANUFACTURING A COMMUTATOR IN PART FROM AN ELECTRICALLY CONDUCTIVE BAND HAVING AN INNER FACE WHICH IN THE FINISHED COMMUTATOR IS DIRECTED TOWARD THE COMMUTATOR AXIS AND AN OUTER FACE WHICH IN THE FINISHED COMMUTATOR IS DIRECTED AWAY FROM SAID AXIS AND HAVING A FLANGE EXTENDING ALONG A SIDE EDGE OF THE BAND AND PROJECTING ONLY FROM SAID OUTER FACE THEREOF, THE STEPS OF PRESSING TWO SERIES OF TRANSVERSE GROOVE FROM OPPOSITE SIDES INTO SAID BAND, ONE SERIES FROM SAID INNER TOWARD SAID OUTER FACE THEREOF TO DEFINE ELONGATED SEGMENT CONNECTED TO EACH OTHER BY BRIDGING PORTIONS LOCATED AT THE OUTER FACE OF THE BAND AND AT THE BASES OF THE GROOVES, RESPECTIVELY, AND THE OTHER SERIES BEING RESPECTIVELY ALIGNED WITH SAID FIRST SERIES OF GROOVES AND EXTENDING INTO SAID FLANGE UP TO SAID OUTER FACE OF SAID BAND, SO THAT EACH SEGMENT IS SUBSTANTIALLY L-SHAPED AND HAS A RELATIVELY LONG LEG EXTENDING SUBSTANTIALLY PERPENDICULARLY RELATIVELY SHORT LEG EXTENDING SUBSTANTIALLY PERPENDICULARLY TO THE BAND; ROLLING A PLURALITY OF THE L-SHAPED SEGMENTS, CONNECTED BY SAID BRIDGING PORTIONS, INTO THE SHAPE OF A CYLINDER WITH SID RELATIVELY SHORT LEGS DIRECTED AWAY FROM THE CYLINDER AXIS; EMBEDDING SAID SEGMENTS IN A CYLINDRICALY BODY OF NON-CONDUCTIVE MATERIAL WHICH FILLS SAID FIRST SERIES OF GROOVES AND WHICH IS SURROUNDED BY THE CYLINDRICAL ROLL OF SEGMENTS; AND REMOVING SAID BRIDGING PROTIONS SO AS TO LEAVE SAID SEGMENTS SEPARATED FROM EACH OTHER AND CONNECTED TOGETHER ONLY BY SAID NON-CONDUCTIVE MATERIAL, SAID SHORTER LEGS OF SAID SEGMENTS BEING ADAPTED TO HAVE ARMATURE LEADS CONNECTED THERETO.

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