Title of Invention	CONDUCTOR BLANK FOR A DRUM COMMUTATOR, METHOD FOR PRODUCTION OF SAME, AND DRUM COMMUTATOR
Abstract	In an annularly closed conductor blank for a drum commutator (T), the conductor segments (4) are joined to one another via bridging parts. These conductor segments are provided with terminal projections (7) disposed on one end face and with inwardly directed anchor ties intended for anchoring the conductor segments in a support member (1). First anchor ties (9a, 9b), which are created by splitting material on the radially inward surface of the strip in the region of the conductor segments (4), form K-shaped anchor-tie pairs. Furthermore, C-shaped second anchor ties (10a, 10b) disposed substantially at the end faces are created by inwardly directed bending back of anchoring projections disposed along the rim of the strip.

Title of Invention

CONDUCTOR BLANK FOR A DRUM COMMUTATOR, METHOD FOR PRODUCTION OF SAME, AND DRUM COMMUTATOR

Abstract

In an annularly closed conductor blank for a drum commutator (T), the conductor segments (4) are joined to one another via bridging parts. These conductor segments are provided with terminal projections (7) disposed on one end face and with inwardly directed anchor ties intended for anchoring the conductor segments in a support member (1). First anchor ties (9a, 9b), which are created by splitting material on the radially inward surface of the strip in the region of the conductor segments (4), form K-shaped anchor-tie pairs. Furthermore, C-shaped second anchor ties (10a, 10b) disposed substantially at the end faces are created by inwardly directed bending back of anchoring projections disposed along the rim of the strip.

Full Text	WO 2007/000219 PCT/EP2006/005035 Conductor blank for a drum commutator, method for production of same, and drum commutator The present invention relates to an annularly closed conductor blank for a drum commutator, with conductor segments that are joined to one another via bridging parts, wherein the conductor segments are provided with terminal projections disposed on one end face and with inwardly directed anchor ties intended for anchoring the conductor segments in a support member. Furthermore, the present invention relates to a method for producing an annularly closed conductor blank for a drum commutator, which blank is provided with conductor segments joined to one another via bridging parts, as well as to a drum commutator produced using the aforesaid conductor blank. Depending on how they are produced, drum commutators are divided into two groups. In a first design (see, for example, DE 1956340, DE 2140855, US 4598463 A, EP 0247221 Al, EP 0243640 Bl, DE 29609538 Ul, DE 10244006 Al), individual laminations that in particular can be stamped out of profile strip are processed. During manufacture of the commutator, the individual laminations are inserted into a mounting cage, which defines the exact location of the laminations during production of the support member in which the laminations are anchored. Drum commutators produced in this design meet very stringent quality requirements, but are relatively expensive to produce, and so in general they are used only in particularly high-performance electrical products. In a second design, a conductor blank produced from a metal strip by rolling and comprising conductor segments joined WO 2007/000219 PCT/EP2006/005035 2 to one another via bridging parts is processed. The support member is injection-molded onto the corresponding annular conductor blank. After the support member has been cured, the bridging parts are removed and in this way the conductor segments are separated from one another. Drum commutators according to this design are the subject matter of, for example, US 4705977 A, US 3492519 A, FR 2458156 A3, US 4872255 A, GB 1561460, EP 0019472 A2, DE 1955122, US 4920633 A, DE 4138829 Al, DE 3307312 Al, EP 0007186 Al, DE 10233712 B3, DE 10306516 Al, DE 2328698, EP 0780029 and WO 01/61796 Al. Compared with the first design mentioned, such drum commutators have much lower production costs. On the other hand, the drum commutators produced in this way have heretofore met only moderate quality requirements. Against the background of the prior art outlined in the foregoing, the object of the present invention is to provide a possibility of producing drum commutators according to the second design mentioned, which commutators are characterized by quality features that meet stringent requirements despite low production costs . To achieve this object, the present invention focuses on the styling of the conductor blank, especially on the styling features that are definitively responsible for anchoring the conductor segments in the support member. According to the present invention, the object specified in the foregoing can be achieved in particular by providing, in an annularly closed conductor blank of the type mentioned hereinabove, first anchor WO 2007/000219 PCT/EP2006/005035 3 tics forming K-shaped anchor-tie pairs and created by splitting material on the radially inward surface' of the strip in the region of the conductor segments, and C-shaped second anchor tics disposed substantially at the end faces and created by inwardly directed bending back of anchoring projections disposed along the rim of the strip. Because of the characteristic combination of d:i Pferonl, specifically shaped and disposed anchor ties provided according to the present invention, there can be surprisingly achieved such good anchoring of the conductor segments in the support member that drum commutators produced inexpensively using an annularly closed conductor blank also meet quality requirements that heretofore were achieved only with complex and expensive drum commutators according to the individual lamination design. For this purpose the invention utilizes the knowledge that the deepest possible anchoring of the conductor segments in the support member is advantageous for the dimensional stability of the commutator, even under high loads. Such deep anchoring of the conductor segments in the support member by correspondingly long first anchor ties of the K-shaped anchor-tie pairs can be achieved, while implementing the present invention, by providing, in addition to that K-shaped anchor-tie pair, C-shaped second anchor ties disposed.substantially at the end faces, and created by inwardly directed bending back of anchoring projections disposed along the rim of the strip. It is only by this end-face anchoring of the conductor segments by means of the C-shaped second anchor ties that it is possible at all to make the first anchor ties sufficiently long that deep anchoring of the conductor segments in the support member is possible therewith. WO 2007/000219 PCT/EP2006/005035 4 This is so because, with increasing length of the first anchor ties, their root points become increasingly distant from the ends of the conductor segments, and so, according to the prior art, the length of the first anchor ties was limited to such a size that only relatively shallow anchoring of the conductor segments in the support member was possible if deformation of the conductor segments was to be prevented effectively. The second anchor ties provided according to the invention can also be made correspondingly long for deep, secure anchoring of the conductor segments in the support member. As a result, and as explained, it is possible, using inventive conductor blanks, to produce drum commutators that meet very stringent quality requirements even under high loads. The first anchor ties are generally machined out of rib-like raised projections on the inside surface of the strip. The corresponding rib-like profiling of the strip can be achieved in various ways known in themselves. Specifically, in the case of relatively small drum commutators, a preferred improvement of the.inventive conductor blank is characters zed in that the radial distance of the free ends of at least one of the respective first anchor ties, of each K-shaped anchor-tie pair from the axis is at most 65% of the radial distance of the radial outside face of the conductor segments from the axis, which face - if necessary with allowance for mechanical post-machining - defines the brush running surface of the drum commutator. WO 2007/000219 PCT/EP2006/005035 5 Particularly preferably, the corresponding distance is less than 50%. For the second, C-shaped anchor ties also, the radial distance of the free ends from the axis is preferably at most 65% and particularly preferably less than 50% of the radial distance of the radial outside face of the conductor segments from the a x i s . According to another preferred improvement of the invention, the free ends of the second anchor ties in the inventive conductor blank have a smaller distance to the axis of the conductor blank than do the first anchor ties. Particularly preferably, each of the second anchor ties then ends substantially inward of the adjacent first anchor ties in radial direction. Under certain prerequisites, however, it may also be favorable if the free ends of the first anchor ties have a shorter distance to the axis of the conductor blank than do the second anchor ties, in which case each of the second anchor ties can end substantially outward of an adjacent first anchor tie in radial direction. For typical applications of drum commutators that embody the present invention, it is favorable if C-shaped second anchor ties arc provided in the region of both end faces of the conductor blank. In this case, the advantages explained in the foregoing arc particularly marked. Ideally, however, the first and second anchor ties adjacent to the terminal projections then end somewhat further inward, in radial direction, than do the first and second anchor ties provided distant from the terminal- projections and thus project somewhat more deeply into the support member in corresponding drum commutators. This results in WO 2007/000219 PCT/EP2006/005035 6 optimal anchoring of the conductor segments with minimal use of material. If a certain loss of quality is tolerated, however, one of each two second anchor ties may also be omitted, so that second anchor ties are provided only in the region of one end face of the conductor blank. From the viewpoint of costs, it is then most, favorable to dispense with second anchor ties at the end face of the conductor blank opposite the terminal projections, since in this case the strip material used for production of the conductor blank can be made narrower. Nevertheless, for drum commutators having a large number of conductor segments, it is recommended that the second anchor ties be dispensed with on that side on which the terminal projections arc disposed, especially if relatively small commutator diameters are to be achieved. Another preferred improvement of the invention i.s characterized in that there are provided, at the end face having the terminal projections, second anchor ties whose root portions are offset radially inward relative to the root portions of the terminal projections. It is not merely in regard to secure anchoring of the conductor segments in the support member of the drum commutator that this is. favorable. To the contrary, such a radial offset of the second anchor ties relative to the terminal projections is also advantageous with regard to a brush running surface that is ideally cylindrical as possible, since the inwardly directed bending-back of the anchoring projections along the rim in order to form the C-shaped second anchor ties at the end faces after rolling of the strip does not lead in this case WO 2007/000219 PCT/EP2006/005035 7 to noteworthy deformation of the conductor segments at their outer surface defining the brush running surface. The foregoing viewpoints can be achieved, for example, if two second anchor ties disposed in pairs on both sides of the respective terminal projection and offset relative thereto in circumferential direction are provided on each conductor segment in the region of the end face provided with the terminal projections. Nevertheless, a particularly preferred improvement is characterized in that precisely one second anchor tie disposed radially inward under the respective terminal projection is provided on each conductor segment in the region of the end face provided with the terminal projections. The corresponding anchoring projection can be formed in particular by splitting a common projection that is also used to form the terminal projections, so that common projections are first provided on the one end edge of the strip, and are then split to produce the terminal projections and also the anchoring projections adjacent thereto, which can be deformed in the same operational step to obtain the inwardly bent second anchoring ties. Such a design is favorable in particular for relatively small-dimension commutators with a large number of commutator segments. According to yet another preferred improvement of the invention, the conductor segments are provided, between the first anchor ties associated with one another in pairs, with an undercut groove extending in circumferential direction. Such an undercut groove can contribute, via additional anchoring of the conductor segments between the two first anchor ties of each K-shaped WO 2007/000219 PCT/EP2006/005035 8 anchor-tie pair, to further reduction of the danger of deformation of the conductor segments and thus to improved dimensional stability of the drum commutator, even at high speeds. Corresponding to the foregoing explanations, and according to the present invention, a method for producing an annularly closed conductor blank for a drum commutator, which blank is provided with conductor segments joined to one another via bridging parts, comprises the following steps: . - providing a plane, pre-profiled metal strip with terminal projections disposed along the rim and anchoring projections also disposed along the rim; roiling the strip; creating first anchor ties, which respectively form a K- shaped anchor-tie pair, by splitting material on the radially inward surface of the strip in the region of the conductor segments; inwardly directed bending back of the anchoring projections along the rim in order to form C-shaped second anchor ties substantially at the end faces. The special advantages of this method can be derived directly from the foregoing explanations of the conductor blank according, to the present invention. Preferably the said strip will be rolled before the first anchor ties are formed; this is favorable with regard to the smallest possible manufacturing expense; WO 2007/000219 PCT/EP2006/005035 9 However, this is not imperative; another option, provided suitable machines and tools are used for the purpose, is to roll the strip only after formation of the first anchor ties. Further preferred improvements of the inventive method can be derived directly from the foregoing explanations on the conductor blank according to the present invention. During application of the present invention, drum, commutators having a support member made of insulating molding compound and conductor segments anchored therein are produced by first injection molding - in a manner known in itself -- a support member onto an inventive conductor blank explained hereinabove and, after injection molding of the support member, removing the bridging parts that at first join the conductor segments to one another, it is particularly advantageous if second anchor ties disposed at the end face opposite the terminal projections end substantially flush with the end face of the support member at their root end. As regards the importance, explained hereinabove, of deep anchoring of the conductor segments in the support member, other preferred improvements of the inventive drum commutator are characterized in that the radial extent of at least one first anchor tie of each K-shaped anchor-tie pair and/or of the second anchor ties is at least 40% of the distance of the root of the anchor tie in question from the shaft bore of the support member. The present invention will be explained in more detail WO 2007/000219 PCT/EP2006/005035 10 hereinafter on the basis of a preferred exemplary embodiment illustrated in the drawing. This drawing shows, in a (ha]f) axia.l section, a drum commutator produced using an inventive conductor blank. Drum commutator T illustrated in the drawing comprises a support member 1 formed from insulating molding compound with a shaft bore 3 disposed concentrically with axis 2 as well as a plurality of conductor segments 4 anchored in the support member. Cylindrical outside face 5 of conductor segments 4 represents brush running surface 6. The individual conductor segments arc obtained in a manner known in itself from an annular conductor blank produced from a strip, in which blank the conductor segments are joined to one another via bridging parts, which are removed after injection molding of support member 1. In the annularly closed conductor blank used for production of the illustrated drum commutator, each conductor segment 4 is provided with a terminal projection 7 disposed on one end face, from which projection a terminal hook 8 for the rotor winding is formed by subsequent bending back, and anchor tics directed inwardly toward axis 2 and designed for anchoring the conductor segments in support member 1, namely two first anchor ties 9a, 9b and two second anchor ties 10a, 10b disposed substantially at the end faces. The two first anchor ties 9a, 9b, which form a K- shaped anchor-tie pair, are created by splitting material on the radially inward surface of the strip in the region of conductor segments 4; in contrast, the two second anchor ties 10a, 10b, WO 2007/000219 PCT/EP2006/005035 11 which arc substantially C-shaped, are created by inwardly directed bending back of anchoring projections disposed along the rim of the strip. In the region of the end face provided with the respective terminal projection 7, a second anchor tie 10a is provided on each conductor segment 4, specifically in such a way that the root portion 11 of second anchor tie 10a is offset radially inward relative to root portion 12 of terminal projection 7. The free ends of second anchor ties 10a and 10b each have a smaller distance to axis 2 of the conductor blank than do the ends of the associated first anchor ties 9a and 9b. This second anchor tie 10a disposed in the region of the end face provided with terminal projections 7 ends radially inward of associated first anchor tie 9a; and second anchor tie 10b disposed in the region of opposite end face 13 ends radially inward of associated second anchor tie 9b. Second anchor tie 10b disposed on end face 13 of the conductor segment opposite terminal projection 7 ends substantially flush at its root end with end face 14 of support member 1. First anchor tie 9a and second anchor tie 10a adjacent to terminal projections 7 end slightly further inward in radial direction than do first and second anchor ties 9b and 10b, which are provided distant from the terminal projections. The radial distance of the free end of first anchor tie 9a at the terminal end from axis 2 is 65% and the radial distance of the free end of associated second anchor tie 10a from axis 2 is 55% of the radial WO 2007/000219 PCT/EP2006/005035 12 distance of radial outside face 5 of the conductor segment from axis 2 . Kach conductor segment 4 is provided between first anchor tics 9a and 9b associated with one another in pairs with an undercut groove 15, which extends in circumferential direction and is filled, with molding compound. WO 2007/000219 PCT/EP2006/005035 13 Claims 1. An annularly closed conductor blank for a drum commutator (T) , with conductor segments (4) that are joined to one another via bridging parts, wherein the conductor segments are provided with terminal projections (7) disposed on one end face and with inwardly directed anchor ties intended for anchoring the conductor segments in a support member (1), characterized in that there are provided first anchor ties (9a, 9b) forming K- shaped anchor-tie pairs and created by splitting material on the radially inward surface of the strip in the region of the conductor segments (4), and C-shaped second anchor ties (10a, 10b) disposed substantially at the end faces and created by inwardly directed bending back of anchoring projections disposed along the rim of the strip. 2. A conductor blank according to claim 1, characterized in that the radial distance of the free ends of at least one of the respective first anchor ties (9a, 9b) from the axis (2) is at most 65% of the radial distance of the radial outside face (5) of the conductor segments (4) from the axis. 3. A conductor blank according to claim 1 or claim 2, characterized in that the radial distance of the free ends of the second anchor ties (10a, 10b) from the axis (2) is at most 65% of the radial distance of the radial outside face (5) of the conductor segments (4) from the axis (2). WO 2007/000219 PCT/EP2006/005035 14 4. A conductor blank according to one of claims 1 to 3, characterized in that the free ends of the second anchor ties (10a, 10b) have a smaller distance to the axis (2) of the conductor blank than do the first anchor ties (9a, 9b). 5. A conductor blank according to claim 4, characterized in that each of the second anchor ties (10a, 10b) ends- substant i.al ly inward of the adjacent first anchor ties (9a, 9b) in radial direction. 6. A conductor blank according to one of claims 1 to 3, characterized in that the free ends of the first anchor ties (9a, 9b) have a shorter distance to the axis (2) of the conductor blank than do the second anchor ties (10a, 10b). 7. A conductor blank according to claim 6, characterized in that each of the second anchor ties (10a, 10b) ends substantially outward of an adjacent first anchor tie (9a, 9b) in radial direction. 8. A conductor blank according to one of claims 1 to 7, characterized in that second anchor ties (10a, 10b) are provided in the region of both end faces.. 9. A conductor blank according to claim 8, characterized in that the first and second anchor ties (9a, 10a) adjacent to the WO 2007/000219 PCT/EP2006/005035 15 terminal projections (7) end further inward, in radial direction, than do the first and second anchor ties (9b, 10b) provided distant from the terminal projections. 10. A conductor blank according to one of claims 1 to 9, characterized in that second anchor ties (10a, 10b) are provided only in the region of one end face of the conductor blank. 11. A conductor blank according to one of claims 1 to 10, characterized in that there are provided, at the end face having the terminal projections (7), second anchor ties (10a) whose root portions (11) are offset radially inward relative to the root portions (12) of the terminal projections. 12. A conductor blank according to claim 11, characterized in that precisely one second anchor tie (10a) disposed radially inward under the respective terminal projection is provided on each conductor segment (4) in the region of the end face provided with the terminal projections (7). 13. A conductor blank according to one of claims 1 to 12, characterized in that the conductor segments (4) are provided, between the first anchor ties (9a, 9b) associated with one another in pairs, with an undercut groove (15) extending in circumferential direction. WO 2007/000219 PCT/EP2006/005035 16 14. A method for producing an annularly closed conductor blank for a drum commutator (T), which blank is provided with conductor segments (4) joined to one another via bridging parts, comprising the following steps: providing a plane, pre-profiled metal strip with terminal projections (7) disposed along the rim and anchoring projections also disposed along the rim; rolling the strip; creating first anchor ties (9a, 9b), which respectively form a K-shaped anchor-tie pair, by splitting material on the radially inward surface of the strip .in the region of the conductor segments; inwardly directed bending back of the anchoring projections along the rim in order to form C-shaped second anchor ties (10a, 10b) substantially at the end faces. 15. A method according to claim 14 characterized in that the strip.is rolled before the first anchor ties (9a, 9b) are formed. 16. A drum commutator (T) having a support member (1) made of insulating molding compound and conductor segments (4) anchored therein, which are produced from a conductor blank according to claim 1 by removing the bridging parts after injection molding of the support member. 17. A drum commutator according to claim 16, characterized in that WO 2007/000219 PCT/EP2006/005035 17 second anchor ties (10b) disposed at the end face (13) opposite the terminal projections (7) end substantially flush with the end face (14) of the support member (1) at the i r root end. 18. A drum commutator according to claim 16 or claim 17, characterized in that the radial extent of at least one first anchor tie (9a, 9b) of each K-shaped anchor-tie pair is at least 40% of the distance of the root of the anchor tie in question from the shaft bore (3) of the support member (1). 19. A drum commutator according to one of claims 16 to 18, characterized in that the radial extent of the second anchor ties (10a, 10b) is at least 4 0% of the distance of the root of the anchor tie in question from the shaft bore (3) of the support member (1). In an annularly closed conductor blank for a drum commutator (T), the conductor segments (4) are joined to one another via bridging parts. These conductor segments are provided with terminal projections (7) disposed on one end face and with inwardly directed anchor ties intended for anchoring the conductor segments in a support member (1). First anchor ties (9a, 9b), which are created by splitting material on the radially inward surface of the strip in the region of the conductor segments (4), form K-shaped anchor-tie pairs. Furthermore, C-shaped second anchor ties (10a, 10b) disposed substantially at the end faces are created by inwardly directed bending back of anchoring projections disposed along the rim of the strip.

Full Text

WO 2007/000219 PCT/EP2006/005035
Conductor blank for a drum commutator, method for production of
same, and drum commutator
The present invention relates to an annularly closed conductor
blank for a drum commutator, with conductor segments that are
joined to one another via bridging parts, wherein the conductor
segments are provided with terminal projections disposed on one
end face and with inwardly directed anchor ties intended for
anchoring the conductor segments in a support member.
Furthermore, the present invention relates to a method for
producing an annularly closed conductor blank for a drum
commutator, which blank is provided with conductor segments
joined to one another via bridging parts, as well as to a drum
commutator produced using the aforesaid conductor blank.
Depending on how they are produced, drum commutators are divided
into two groups. In a first design (see, for example, DE 1956340,
DE 2140855, US 4598463 A, EP 0247221 Al, EP 0243640 Bl, DE
29609538 Ul, DE 10244006 Al), individual laminations that in
particular can be stamped out of profile strip are processed.
During manufacture of the commutator, the individual laminations
are inserted into a mounting cage, which defines the exact
location of the laminations during production of the support
member in which the laminations are anchored. Drum commutators
produced in this design meet very stringent quality requirements,
but are relatively expensive to produce, and so in general they
are used only in particularly high-performance electrical
products. In a second design, a conductor blank produced from a
metal strip by rolling and comprising conductor segments joined

WO 2007/000219 PCT/EP2006/005035
2
to one another via bridging parts is processed. The support
member is injection-molded onto the corresponding annular
conductor blank. After the support member has been cured, the
bridging parts are removed and in this way the conductor segments
are separated from one another. Drum commutators according to
this design are the subject matter of, for example, US 4705977 A,
US 3492519 A, FR 2458156 A3, US 4872255 A, GB 1561460, EP 0019472
A2, DE 1955122, US 4920633 A, DE 4138829 Al, DE 3307312 Al, EP
0007186 Al, DE 10233712 B3, DE 10306516 Al, DE 2328698, EP
0780029 and WO 01/61796 Al. Compared with the first design
mentioned, such drum commutators have much lower production
costs. On the other hand, the drum commutators produced in this
way have heretofore met only moderate quality requirements.
Against the background of the prior art outlined in the
foregoing, the object of the present invention is to provide a
possibility of producing drum commutators according to the second
design mentioned, which commutators are characterized by quality
features that meet stringent requirements despite low production
costs .
To achieve this object, the present invention focuses on the
styling of the conductor blank, especially on the styling
features that are definitively responsible for anchoring the
conductor segments in the support member. According to the
present invention, the object specified in the foregoing can be
achieved in particular by providing, in an annularly closed
conductor blank of the type mentioned hereinabove, first anchor

WO 2007/000219 PCT/EP2006/005035
3
tics forming K-shaped anchor-tie pairs and created by splitting
material on the radially inward surface' of the strip in the
region of the conductor segments, and C-shaped second anchor tics
disposed substantially at the end faces and created by inwardly
directed bending back of anchoring projections disposed along the
rim of the strip. Because of the characteristic combination of
d:i Pferonl, specifically shaped and disposed anchor ties provided
according to the present invention, there can be surprisingly
achieved such good anchoring of the conductor segments in the
support member that drum commutators produced inexpensively using
an annularly closed conductor blank also meet quality
requirements that heretofore were achieved only with complex and
expensive drum commutators according to the individual lamination
design. For this purpose the invention utilizes the knowledge
that the deepest possible anchoring of the conductor segments in
the support member is advantageous for the dimensional stability
of the commutator, even under high loads. Such deep anchoring of
the conductor segments in the support member by correspondingly
long first anchor ties of the K-shaped anchor-tie pairs can be
achieved, while implementing the present invention, by providing,
in addition to that K-shaped anchor-tie pair, C-shaped second
anchor ties disposed.substantially at the end faces, and created
by inwardly directed bending back of anchoring projections
disposed along the rim of the strip. It is only by this end-face
anchoring of the conductor segments by means of the C-shaped
second anchor ties that it is possible at all to make the first
anchor ties sufficiently long that deep anchoring of the
conductor segments in the support member is possible therewith.

WO 2007/000219 PCT/EP2006/005035
4
This is so because, with increasing length of the first anchor
ties, their root points become increasingly distant from the ends
of the conductor segments, and so, according to the prior art,
the length of the first anchor ties was limited to such a size
that only relatively shallow anchoring of the conductor segments
in the support member was possible if deformation of the
conductor segments was to be prevented effectively. The second
anchor ties provided according to the invention can also be made
correspondingly long for deep, secure anchoring of the conductor
segments in the support member. As a result, and as explained, it
is possible, using inventive conductor blanks, to produce drum
commutators that meet very stringent quality requirements even
under high loads.
The first anchor ties are generally machined out of rib-like
raised projections on the inside surface of the strip. The
corresponding rib-like profiling of the strip can be achieved in
various ways known in themselves.
Specifically, in the case of relatively small drum commutators, a
preferred improvement of the.inventive conductor blank is
characters zed in that the radial distance of the free ends of at
least one of the respective first anchor ties, of each K-shaped
anchor-tie pair from the axis is at most 65% of the radial
distance of the radial outside face of the conductor segments
from the axis, which face - if necessary with allowance for
mechanical post-machining - defines the brush running surface of
the drum commutator.

WO 2007/000219 PCT/EP2006/005035
5
Particularly preferably, the corresponding distance is less than
50%. For the second, C-shaped anchor ties also, the radial
distance of the free ends from the axis is preferably at most 65%
and particularly preferably less than 50% of the radial distance
of the radial outside face of the conductor segments from the
a x i s .
According to another preferred improvement of the invention, the
free ends of the second anchor ties in the inventive conductor
blank have a smaller distance to the axis of the conductor blank
than do the first anchor ties. Particularly preferably, each of
the second anchor ties then ends substantially inward of the
adjacent first anchor ties in radial direction. Under certain
prerequisites, however, it may also be favorable if the free ends
of the first anchor ties have a shorter distance to the axis of
the conductor blank than do the second anchor ties, in which case
each of the second anchor ties can end substantially outward of
an adjacent first anchor tie in radial direction.
For typical applications of drum commutators that embody the
present invention, it is favorable if C-shaped second anchor ties
arc provided in the region of both end faces of the conductor
blank. In this case, the advantages explained in the foregoing
arc particularly marked. Ideally, however, the first and second
anchor ties adjacent to the terminal projections then end
somewhat further inward, in radial direction, than do the first
and second anchor ties provided distant from the terminal-
projections and thus project somewhat more deeply into the
support member in corresponding drum commutators. This results in

WO 2007/000219 PCT/EP2006/005035
6
optimal anchoring of the conductor segments with minimal use of
material. If a certain loss of quality is tolerated, however, one
of each two second anchor ties may also be omitted, so that
second anchor ties are provided only in the region of one end
face of the conductor blank. From the viewpoint of costs, it is
then most, favorable to dispense with second anchor ties at the
end face of the conductor blank opposite the terminal
projections, since in this case the strip material used for
production of the conductor blank can be made narrower.
Nevertheless, for drum commutators having a large number of
conductor segments, it is recommended that the second anchor ties
be dispensed with on that side on which the terminal projections
arc disposed, especially if relatively small commutator diameters
are to be achieved.
Another preferred improvement of the invention i.s characterized
in that there are provided, at the end face having the terminal
projections, second anchor ties whose root portions are offset
radially inward relative to the root portions of the terminal
projections. It is not merely in regard to secure anchoring of
the conductor segments in the support member of the drum
commutator that this is. favorable. To the contrary, such a radial
offset of the second anchor ties relative to the terminal
projections is also advantageous with regard to a brush running
surface that is ideally cylindrical as possible, since the
inwardly directed bending-back of the anchoring projections along
the rim in order to form the C-shaped second anchor ties at the
end faces after rolling of the strip does not lead in this case

WO 2007/000219 PCT/EP2006/005035
7
to noteworthy deformation of the conductor segments at their
outer surface defining the brush running surface. The foregoing
viewpoints can be achieved, for example, if two second anchor
ties disposed in pairs on both sides of the respective terminal
projection and offset relative thereto in circumferential
direction are provided on each conductor segment in the region of
the end face provided with the terminal projections.
Nevertheless, a particularly preferred improvement is
characterized in that precisely one second anchor tie disposed
radially inward under the respective terminal projection is
provided on each conductor segment in the region of the end face
provided with the terminal projections. The corresponding
anchoring projection can be formed in particular by splitting a
common projection that is also used to form the terminal
projections, so that common projections are first provided on the
one end edge of the strip, and are then split to produce the
terminal projections and also the anchoring projections adjacent
thereto, which can be deformed in the same operational step to
obtain the inwardly bent second anchoring ties. Such a design is
favorable in particular for relatively small-dimension
commutators with a large number of commutator segments.
According to yet another preferred improvement of the invention,
the conductor segments are provided, between the first anchor
ties associated with one another in pairs, with an undercut
groove extending in circumferential direction. Such an undercut
groove can contribute, via additional anchoring of the conductor
segments between the two first anchor ties of each K-shaped

WO 2007/000219 PCT/EP2006/005035
8
anchor-tie pair, to further reduction of the danger of
deformation of the conductor segments and thus to improved
dimensional stability of the drum commutator, even at high
speeds.
Corresponding to the foregoing explanations, and according to the
present invention, a method for producing an annularly closed
conductor blank for a drum commutator, which blank is provided
with conductor segments joined to one another via bridging parts,
comprises the following steps:
. - providing a plane, pre-profiled metal strip with terminal
projections disposed along the rim and anchoring projections
also disposed along the rim;
roiling the strip;
creating first anchor ties, which respectively form a K-
shaped anchor-tie pair, by splitting material on the
radially inward surface of the strip in the region of the
conductor segments;
inwardly directed bending back of the anchoring projections
along the rim in order to form C-shaped second anchor ties
substantially at the end faces.
The special advantages of this method can be derived directly
from the foregoing explanations of the conductor blank according,
to the present invention. Preferably the said strip will be
rolled before the first anchor ties are formed; this is favorable
with regard to the smallest possible manufacturing expense;

WO 2007/000219 PCT/EP2006/005035
9
However, this is not imperative; another option, provided
suitable machines and tools are used for the purpose, is to roll
the strip only after formation of the first anchor ties. Further
preferred improvements of the inventive method can be derived
directly from the foregoing explanations on the conductor blank
according to the present invention.
During application of the present invention, drum, commutators
having a support member made of insulating molding compound and
conductor segments anchored therein are produced by first
injection molding - in a manner known in itself -- a support
member onto an inventive conductor blank explained hereinabove
and, after injection molding of the support member, removing the
bridging parts that at first join the conductor segments to one
another, it is particularly advantageous if second anchor ties
disposed at the end face opposite the terminal projections end
substantially flush with the end face of the support member at
their root end. As regards the importance, explained hereinabove,
of deep anchoring of the conductor segments in the support
member, other preferred improvements of the inventive drum
commutator are characterized in that the radial extent of at
least one first anchor tie of each K-shaped anchor-tie pair
and/or of the second anchor ties is at least 40% of the distance
of the root of the anchor tie in question from the shaft bore of
the support member.
The present invention will be explained in more detail

WO 2007/000219 PCT/EP2006/005035
10
hereinafter on the basis of a preferred exemplary embodiment
illustrated in the drawing. This drawing shows, in a (ha]f) axia.l
section, a drum commutator produced using an inventive conductor
blank.
Drum commutator T illustrated in the drawing comprises a support
member 1 formed from insulating molding compound with a shaft
bore 3 disposed concentrically with axis 2 as well as a plurality
of conductor segments 4 anchored in the support member.
Cylindrical outside face 5 of conductor segments 4 represents
brush running surface 6. The individual conductor segments arc
obtained in a manner known in itself from an annular conductor
blank produced from a strip, in which blank the conductor
segments are joined to one another via bridging parts, which are
removed after injection molding of support member 1.
In the annularly closed conductor blank used for production of
the illustrated drum commutator, each conductor segment 4 is
provided with a terminal projection 7 disposed on one end face,
from which projection a terminal hook 8 for the rotor winding is
formed by subsequent bending back, and anchor tics directed
inwardly toward axis 2 and designed for anchoring the conductor
segments in support member 1, namely two first anchor ties 9a, 9b
and two second anchor ties 10a, 10b disposed substantially at the
end faces. The two first anchor ties 9a, 9b, which form a K-
shaped anchor-tie pair, are created by splitting material on the
radially inward surface of the strip in the region of conductor
segments 4; in contrast, the two second anchor ties 10a, 10b,

WO 2007/000219 PCT/EP2006/005035
11
which arc substantially C-shaped, are created by inwardly
directed bending back of anchoring projections disposed along the
rim of the strip. In the region of the end face provided with the
respective terminal projection 7, a second anchor tie 10a is
provided on each conductor segment 4, specifically in such a way
that the root portion 11 of second anchor tie 10a is offset
radially inward relative to root portion 12 of terminal
projection 7.
The free ends of second anchor ties 10a and 10b each have a
smaller distance to axis 2 of the conductor blank than do the
ends of the associated first anchor ties 9a and 9b. This second
anchor tie 10a disposed in the region of the end face provided
with terminal projections 7 ends radially inward of associated
first anchor tie 9a; and second anchor tie 10b disposed in the
region of opposite end face 13 ends radially inward of associated
second anchor tie 9b. Second anchor tie 10b disposed on end face
13 of the conductor segment opposite terminal projection 7 ends
substantially flush at its root end with end face 14 of support
member 1.
First anchor tie 9a and second anchor tie 10a adjacent to
terminal projections 7 end slightly further inward in radial
direction than do first and second anchor ties 9b and 10b, which
are provided distant from the terminal projections. The radial
distance of the free end of first anchor tie 9a at the terminal
end from axis 2 is 65% and the radial distance of the free end of
associated second anchor tie 10a from axis 2 is 55% of the radial

WO 2007/000219 PCT/EP2006/005035
12
distance of radial outside face 5 of the conductor segment from
axis 2 .
Kach conductor segment 4 is provided between first anchor tics 9a
and 9b associated with one another in pairs with an undercut
groove 15, which extends in circumferential direction and is
filled, with molding compound.

WO 2007/000219 PCT/EP2006/005035
13
Claims
1. An annularly closed conductor blank for a drum commutator
(T) , with conductor segments (4) that are joined to one
another via bridging parts, wherein the conductor segments
are provided with terminal projections (7) disposed on one
end face and with inwardly directed anchor ties intended for
anchoring the conductor segments in a support member (1),
characterized in that
there are provided first anchor ties (9a, 9b) forming K-
shaped anchor-tie pairs and created by splitting material on
the radially inward surface of the strip in the region of
the conductor segments (4), and C-shaped second anchor ties
(10a, 10b) disposed substantially at the end faces and
created by inwardly directed bending back of anchoring
projections disposed along the rim of the strip.
2. A conductor blank according to claim 1,
characterized in that
the radial distance of the free ends of at least one of the
respective first anchor ties (9a, 9b) from the axis (2) is
at most 65% of the radial distance of the radial outside
face (5) of the conductor segments (4) from the axis.
3. A conductor blank according to claim 1 or claim 2,
characterized in that
the radial distance of the free ends of the second anchor
ties (10a, 10b) from the axis (2) is at most 65% of the
radial distance of the radial outside face (5) of the
conductor segments (4) from the axis (2).

WO 2007/000219 PCT/EP2006/005035
14
4. A conductor blank according to one of claims 1 to 3,
characterized in that
the free ends of the second anchor ties (10a, 10b) have a
smaller distance to the axis (2) of the conductor blank than
do the first anchor ties (9a, 9b).
5. A conductor blank according to claim 4,
characterized in that
each of the second anchor ties (10a, 10b) ends- substant i.al ly
inward of the adjacent first anchor ties (9a, 9b) in radial
direction.
6. A conductor blank according to one of claims 1 to 3,
characterized in that
the free ends of the first anchor ties (9a, 9b) have a
shorter distance to the axis (2) of the conductor blank than
do the second anchor ties (10a, 10b).
7. A conductor blank according to claim 6,
characterized in that
each of the second anchor ties (10a, 10b) ends substantially
outward of an adjacent first anchor tie (9a, 9b) in radial
direction.
8. A conductor blank according to one of claims 1 to 7,
characterized in that
second anchor ties (10a, 10b) are provided in the region of
both end faces..
9. A conductor blank according to claim 8,
characterized in that
the first and second anchor ties (9a, 10a) adjacent to the

WO 2007/000219 PCT/EP2006/005035
15
terminal projections (7) end further inward, in radial
direction, than do the first and second anchor ties (9b,
10b) provided distant from the terminal projections.
10. A conductor blank according to one of claims 1 to 9,
characterized in that
second anchor ties (10a, 10b) are provided only in the
region of one end face of the conductor blank.
11. A conductor blank according to one of claims 1 to 10,
characterized in that
there are provided, at the end face having the terminal
projections (7), second anchor ties (10a) whose root
portions (11) are offset radially inward relative to the
root portions (12) of the terminal projections.
12. A conductor blank according to claim 11,
characterized in that
precisely one second anchor tie (10a) disposed radially
inward under the respective terminal projection is provided
on each conductor segment (4) in the region of the end face
provided with the terminal projections (7).
13. A conductor blank according to one of claims 1 to 12,
characterized in that
the conductor segments (4) are provided, between the first
anchor ties (9a, 9b) associated with one another in pairs,
with an undercut groove (15) extending in circumferential
direction.

WO 2007/000219 PCT/EP2006/005035
16
14. A method for producing an annularly closed conductor blank
for a drum commutator (T), which blank is provided with
conductor segments (4) joined to one another via bridging
parts, comprising the following steps:
providing a plane, pre-profiled metal strip with
terminal projections (7) disposed along the rim and
anchoring projections also disposed along the rim;
rolling the strip;
creating first anchor ties (9a, 9b), which respectively
form a K-shaped anchor-tie pair, by splitting material
on the radially inward surface of the strip .in the
region of the conductor segments;
inwardly directed bending back of the anchoring
projections along the rim in order to form C-shaped
second anchor ties (10a, 10b) substantially at the end
faces.
15. A method according to claim 14
characterized in that
the strip.is rolled before the first anchor ties (9a, 9b)
are formed.
16. A drum commutator (T) having a support member (1) made of
insulating molding compound and conductor segments (4)
anchored therein, which are produced from a conductor blank
according to claim 1 by removing the bridging parts after
injection molding of the support member.
17. A drum commutator according to claim 16,
characterized in that

WO 2007/000219 PCT/EP2006/005035
17
second anchor ties (10b) disposed at the end face (13)
opposite the terminal projections (7) end substantially
flush with the end face (14) of the support member (1) at
the i r root end.
18. A drum commutator according to claim 16 or claim 17,
characterized in that
the radial extent of at least one first anchor tie (9a, 9b)
of each K-shaped anchor-tie pair is at least 40% of the
distance of the root of the anchor tie in question from the
shaft bore (3) of the support member (1).
19. A drum commutator according to one of claims 16 to 18,
characterized in that
the radial extent of the second anchor ties (10a, 10b) is at
least 4 0% of the distance of the root of the anchor tie in
question from the shaft bore (3) of the support member (1).

In an annularly closed conductor blank for a drum commutator (T), the
conductor segments (4) are joined to one another via bridging parts. These
conductor segments are provided with terminal projections (7) disposed on
one end face and with inwardly directed anchor ties intended for anchoring
the conductor segments in a support member (1). First anchor ties (9a, 9b),
which are created by splitting material on the radially inward surface of the
strip in the region of the conductor segments (4), form K-shaped anchor-tie
pairs. Furthermore, C-shaped second anchor ties (10a, 10b) disposed
substantially at the end faces are created by inwardly directed bending back
of anchoring projections disposed along the rim of the strip.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=paVq2B/weVFlJ9mWqVU7Rg==&loc=wDBSZCsAt7zoiVrqcFJsRw==

« Previous Patent

Next Patent »

Patent Number

271518

Indian Patent Application Number

4598/KOLNP/2007

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

24-Feb-2016

Date of Filing

28-Nov-2007

Name of Patentee

KOLEKTOR GROUP D.O.O.

Applicant Address

VOJKOVA 10, P.P. 85, 5280 IDRIJA

Inventors:

#	Inventor's Name	Inventor's Address
1	VIHTELIC, MARKO	POT V CESNICE NO. 2, 5280 IDRIJA

PCT International Classification Number

H01R 39/04

PCT International Application Number

PCT/EP2006/005035

PCT International Filing date

2006-05-26

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2005 030 454.0	2005-06-28	Germany