EP0821838A1

EP0821838A1 - Collector manufacturing process

Info

Publication number: EP0821838A1
Application number: EP96914933A
Authority: EP
Inventors: Anton Holzhauer
Original assignee: Firma Anton Holzhauer Umformtechnik
Current assignee: Firma Anton Holzhauer Umformtechnik
Priority date: 1995-04-21
Filing date: 1996-04-17
Publication date: 1998-02-04
Anticipated expiration: 2016-04-17
Also published as: JPH11509029A; ES2131397T3; SK142297A3; ZA963158B; SI9620054A; KR19990007946A; AU5689296A; JP4301528B2; DE59601501D1; EP0821838B1; CA2218487A1; US6108898A; HUP9801535A2; HUP9801535A3; CN1187911A; DE19514795C1; CN1068718C; AU722392B2; BR9608186A; WO1996033534A1

Abstract

A process is disclosed for manufacturing collectors, in particular flat collectors for electric machines. The individual connection elements (2) are at first directly shaped by crowding in a substantially non-machined raw conductive material (1) with their final contour and size and in their final ductile state. For that purpose, a warm forming process is used. The raw material (1) is warmed before the connection elements (2) are formed so that it does not significantly consolidate while the connection elements (2) are formed by crowding, and forming is then carried out in the warm state. In addition, a pot-shaped blank (3) may be shaped, preferably in a cold forming step, for example with inner shaped anchoring elements (6) for an insulating lining. Recesses (9) may be shaped by crowding on the cylindrical envelope (4) of the pot-shaped blank (3). These recesses are associated to the segment divisions and extend almost down to the bottom (5) of the pot-shaped blank (3). In a subsequent forming step, outer anchoring elements (13) are formed on the cylindrical envelope (4), if required a central opening (14) is cut out in the bottom (5) and the previously shaped inner anchoring elements (6) are bent outwards in the radial direction.

Description

Method of manufacturing a commutator

description

The invention relates to a method for producing a commutator, in particular a flat commutator, for electrical machines according to the preamble of claim 1.

DE 41 40 475 C2 discloses a method for producing a planar commutator of the type mentioned above. In this case, an essentially unprocessed raw material made of conductive material is assumed, which is preferably present in rod material, from which a starting body is cut off, for example in the form of a round blank. By means of extrusion, this base body is formed into a pot-shaped blank, which has an annular plan part and an adjoining tubular jacket. In the course of the multi-stage reshaping, inner anchoring elements and outer anchoring elements arranged in a ring shape are formed in order to reliably anchor the molding compound, which serves as an insulating compound, to be subsequently accommodated in the pot-shaped interior of the blank, with the commutator. In a further operation, a radially outwardly projecting ring flange is molded onto the free end of the jacket of the cup-shaped blank, specifically by material displacement in the axial direction towards the free end of the jacket. In a further step, the flag-shaped connecting elements are obtained by punching them out of the ring flange previously formed. During this punching process, the outer anchoring elements are also split off. By punching the connecting elements out of the continuous

SPARE BLADE (RULE 26) The previously formed ring flange at the free end of the jacket of the blank produces waste material which remains unused, the remaining and punched-out connecting elements in particular taking up only a small fraction of the total ring flange area, so that a relatively large amount of material is lost in this production.

Another difficulty can be seen in the fact that in the various extrusion treatments and also in the formation of the ring flange, material deformation is inevitably brought about by the deformation, so that the connecting elements formed are less ductile or bendable than the starting raw material. After the completion of the commutator, however, connecting wires are wrapped around these connecting elements and then the connecting elements are bent back onto the outside of the cylindrical jacket. As a result of the embrittlement of the material, cracks have therefore occurred in the customary production method and these are generally to be feared. The known manufacturing method also includes a large number of individual deformation steps, which affects the economical manufacturing of such commutators.

From US-A-3812576, the disadvantages and difficulties of which are to be overcome with DE 41 40 475 C2, dealt with above, a method for producing a commutator for electrical machines is known in which a cylindrical part is produced starting from a disk-shaped, conductive raw material , which has an open end with a radially outwardly projecting, continuous ring flange and a bottom. By pressing, recessed parts are formed from the inside of the cylindrical portion of the cylindrical part, which prevent the insulating material from adhering to the ring flange or the outer surface of the bottom when the insulating material is filled later. The ring flange is then machined by punching in such a way that flag-shaped connecting elements remain, and the recessed ones

REPLACEMENT BLUE (RULE 26) Sections as well as the punched-out parts of the ring flange are removed.

Apart from the large number of individual operations, waste material is also produced when the flag-shaped connecting elements are punched free, and there is a risk that the individual flag-shaped connecting elements finally obtained by punching free form material consolidation or embrittlement due to the individual forming operations.

In contrast, the object of the invention is to provide a method for producing a commutator, in particular a flat commutator, of the generic type while overcoming the difficulties described above, which allows economical and material-saving production, and in which, in particular, the connecting elements are ductile or ductile after molding are bendable and remain bendable until the bending process is carried out.

According to the invention, a method for producing a commutator, in particular a flat commutator, for electrical machines is provided for this purpose, which is made of an essentially unprocessed raw material made of conductive material to form a plurality of segments which are insulated from one another and comprise insulating material and which have radially allocated segments individually protruding connecting elements is produced, the manufacturing process being characterized in that the raw material is first formed to form the individual connecting elements with finished contour and size as well as with a ductile finished state.

In deviation from the previous manufacturing methods for commutators, the individual connecting elements are thus first formed by reshaping the material starting from the raw material by displacing the material. It is essential here that these connection elements

ERSÄTZBLÄΪT (RULE 26) This forming process has its finished shape and size and is in a ductile finished state, which is retained until the final bending process. This direct shaping of the individual connection elements on the raw material base body avoids subsequent machining operations, such as punching and the like, since the connection elements formed in this way already have their finished contour and size. Thus, no waste material is produced in the method according to the invention, since no continuous ring flange is formed, but only the individual tab-shaped connection elements which protrude in the radial direction on the outer edge of the raw material base body. In particular, it can also be achieved in this way that the connecting elements are ductile or bendable, since they were shaped before the further subsequent forming operations and are no longer exposed to any deformation which could lead to material hardening or embrittlement. In this way, a commutator is produced economically and in a material-saving manner in the method according to the invention.

According to a preferred procedure, the raw material is heated prior to the forming to form the connecting elements, depending on the selected starting material or raw material, in such a way that a notable strengthening of the forming material can be avoided when the connecting elements are formed. As a result, the ductility of the shaped connection elements can be improved and the ductility of the latter essentially depends on the properties of the raw material.

According to a particularly preferred method of production according to the invention, the connection elements are shaped in the thus heated state of the raw material, such a treatment being referred to as semi-hot presses, so that the raw material is transferred to the press immediately after the heating and in the still warm state The connection elements are shaped. The material can be formed if necessary

ERSATZBLAH (REGEL26) Forging and / or at forging temperature. The connection elements are preferably shaped in the semi-warm or warm area.

A temperature of about 150 ^° C. and higher has proven to be expedient for heating the raw material, which of course depends on the raw material used. In the case of copper and its alloys in particular, the temperatures occurring here are subject to large fluctuations and no absolute temperature values can be given for this. Expediently, the heating is carried out of the raw material to a Tempera¬ structure in a range from about 300 to about 700 C. ^β

An alternative production method for the formation of the individual connection elements with finished contour and size as well as with a ductile finished state is characterized in that the raw material is annealed before the formation to form the connection elements, the connection elements are formed by cold forming and then an annealing treatment is carried out again. In this way it can also be avoided, for example, that the connection elements become less ductile after the shaping due to material hardening and embrittlement brought about during the shaping. However, such a method of production is time-consuming since cooling times must elapse after the annealing treatments.

Starting from this state that the raw material has first been formed to form the individual connection elements in accordance with the above description, cold forming then takes place, in which a pot-shaped blank is formed with an essentially cylindrical jacket and an essentially flat bottom. For this area of the commutator, material hardening is desirable for reasons of wear and tear, which can be obtained in a targeted manner, in particular in the flat bottom area of the pot-shaped blank, by the cold-forming treatment. Cold forming also forms inner anchoring elements for the insulating material filling, which are arranged in a ring shape and extend essentially axially on the inner surface of the base. Recesses assigned to the segment division are expediently formed, starting from the free edge of the jacket, by material displacement by cold forming. These recesses extend close to the inner surface of the bottom of the pot-shaped blank. Preferably, the clear width of the recess, starting from the free edge of the jacket, can become smaller in the direction of the bottom, and in particular the recesses formed by material displacement are V-shaped. The "tip region" of the respective V-shaped recess is preferably formed by a short straight section. The number of these recesses corresponds to the number of segments of the commutator and they are assigned to the respective divisions. Since these recesses extend close to the inner surface of the bottom of the pot-shaped blank, the subsequent cutting machining to divide the individual segments from the flat outer surface of the base requires the smallest possible depths of cut so that on the one hand the filled insulating material is not cut deeply must, and on the other hand, the cutting processing can be carried out quickly and easily.

Narrow, radially extending depressions can be formed on the inner surface of the bottom, which start from the "tip area" of the respective recesses and extend to the center of the bottom area. The depth of cut can be reduced even further and is even less than the base material thickness of the floor. Furthermore, the depressions provide reliable guidance during the cutting and sawing operations for dividing and separating the segments of the commutator.

According to a preferred method of manufacturing a commutator according to the invention, the cold working is used for training

ERSATZBLAH RULE26 of the pot-shaped blank, to form the ring-shaped inner anchoring elements and the recesses formed by material displacement, and optionally to form the radial recesses in one work step. In this way, a particularly economical way of producing such a commutator is achieved, since one has very short processing times for cold forming in the manufacturing method according to the invention.

Furthermore, in the method according to the invention, outer anchoring elements for the insulating material filling, which point radially inwards, are formed by cold forming.

If an unperforated raw material made of conductive material is used in the manufacture of the commutator according to the invention, a central opening is punched out for the rotor shaft of the electrical machine in the bottom of the pot-shaped blank. If you start from a perforated raw material or from a bar material with a tubular cross-section and large wall thickness, this processing step can of course be omitted.

Furthermore, the inner anchoring elements are bent slightly radially outward in order to improve the anchoring effect with the later filled insulating material and the insulating material filling.

According to a preferred embodiment of the manufacturing method according to the invention, the processing for forming the radially inward-pointing outer anchoring elements, for punching out the central opening in the bottom of the pot-shaped blank and for bending the inner anchoring elements radially outward are carried out in one work step. As a result, the manufacturing times for such a commutator can be shortened considerably, since one can see overall

SPARE BLADE (RULE 26) the method according to the invention, for example, essentially requires only three forming steps from the raw material to the finished commutator without insulating material filling and aftertreatment or postprocessing.

All further processing and treatments, such as introducing the insulating material filling, if necessary tinning the base body and severing the segments by cutting along the segment divisions and attaching lead wires to the connection elements and bending them over, can then be carried out in the usual way. The bending process for the connection elements is considerably simplified thanks to the manufacturing method according to the invention, and cracks due to material embrittlement can be avoided since the connection elements are in the ductile state without material hardening due to the forming processes. Furthermore, there is an undisturbed fiber course due to the forming process, so that the commutator can withstand the high dynamic loads that occur in particular in motor vehicles.

The production method according to the invention is suitable for the production of commutators of different designs and types, and the invention is not limited to the production of flat commutators. What is essential in the production of all of these types of commutators is the fact that the connection elements are formed on the one hand in such a way that no material waste occurs, and on the other hand that these connection elements with finished contour and size as well as with a ductile finished state right at the beginning of the production by material displacement be shaped. This material displacement takes place, seen from the raw material base body for the formation of the connection elements in the outward direction. Depending on the design of the commutator, the anchoring elements for the insulating material filling can of course be shaped in a correspondingly modified manner without the protective concept according to the invention being abandoned

ERSATZBLAH (REGEL26) which the Ausfor tion of the connecting elements directly from the raw material by material displacement to the finished contour and - large and with a ductile finished state.

The invention is explained in more detail below with the aid of a preferred embodiment with reference to the attached drawing, which, however, does not represent any limitation. The drawing shows:

1 is a perspective view of a raw material base body,

2 is a perspective view in the state with the individual connecting elements obtained by reshaping and material displacement,

3 is a perspective view to illustrate a pot-shaped blank with inner anchoring elements, and

4 shows a perspective view of a pot-shaped blank, in which a central opening is provided and outer anchoring elements are additionally formed.

The method according to the invention is explained using only one example in connection with the production of a base body for a flat commutator. Of course, commutators of other designs can also be manufactured and shaped in the same or a similar manner.

FIG. 1 shows an example of an essentially unprocessed raw material 1. This raw material 1 is shown, for example, as a flat, solid disc which is sheared off and formed by a round rod material. If necessary, deviations from FIG. 1 cannot be specified raw material shown are taken as starting material, which is designed for example as an annular disc and already has a prefabricated central opening 14 ', as indicated in Figure 1 with a broken line. The basic body of the raw material 1 can alternatively be obtained by punching out a strip material with or without a bore. If a thick-walled tube and rod material is used as the starting material, the disk can be in the form of a round blank as raw material 1. All of these starting materials can be used as raw material 1 in the method according to the invention and it is assumed that a solid material in the form of a disk is used as an example, for the explanation below. If necessary, a round blank can also be obtained from such a solid material disc by punching out a central opening as a kind of preprocessing step (not shown).

Starting from the raw material 1 according to FIG. 1, individual connecting elements 2 are then first formed by reshaping, which are, for example, flag-shaped according to FIG. 2. These connection elements 2 protrude radially beyond the peripheral edge of the raw material 1 according to FIG. 1 as individual connection elements 2 and these are shaped such that, as shown in FIG. 2, they have their finished shape and size. These connection elements 2 also have their ductile finished state. Specifically according to a preferred method of production, the raw material 1 is heated before the connection elements 2 are formed, depending on the material properties, in such a way that a notable U-shape material hardening can be avoided. In this heated state, the connection elements 2 with the finished and final state are then preferably molded. Such a shape can be referred to, for example, as a warm press. Formation in the normal range is of course also possible. When the connecting elements 2 are formed, the material of the raw material 1 is displaced outward, preferably while still warm, and the corresponding ones

SPARE BLADE RULE26) Forming tools which are used for this purpose have assigned spaces which specify and limit the finished contour and size of the connection elements 2.

Since the temperatures required for this depend on the properties of the conductive material used for the raw material 1, in particular, for example, on copper alloys, only preferred ranges can be specified. It has been shown here that heating to a temperature of approximately 150 ° C. is expedient. This temperature can of course also be higher. A temperature range of approximately 300 to approximately 700 ° C. has preferably resulted.

As an alternative to semi-hot pressing, cold shaping of the connection elements 2 is also possible. In this case, for example, the raw material 1 can then be annealed, and after cooling, the connection elements 2 according to FIG. 2 are then shaped with the finished contour and size. In order to achieve the desired ductility of the connection elements 2, these can be annealed individually or the entire base body shown in FIG. 2.

FIG. 3 shows a commutator blank 3 which is obtained from the body according to FIG. 2 by cold forming. This blank 3 is pot-shaped and has an essentially cylindrical jacket 4 and a substantially flat bottom 5. At the same time as the pot-shaped blank 3 is formed, inner anchoring elements 6 are formed, which are arranged in a ring shape on an inner surface 7 of the bottom 5 of the pot-shaped blank 3 are. As shown, these inner anchoring elements 6 run essentially axially with respect to the blank 3 and protrude in a jagged manner from the inner surface 7 of the base 5.

SPARE BLADE RULE 26 As shown, the forming process starting from FIG. 2 to the cup-shaped blank 3 according to FIG. 3 is preferably carried out in a single forming step. Of course, the forming operations can also be carried out one after the other, if necessary.

If necessary, a number of recesses 9 can be formed at the same time as the shaping treatment starting from FIG. 2 to FIG. 3 by material displacement. The number of recesses 9 corresponds to the number of segment division and in the embodiment shown there are eight such recesses 9. According to the preferred embodiment shown, each recess 9 starts from a free edge 10 of the cylindrical jacket 4 and extends close to the bottom 5 of the cup-shaped blank 3. Preferably, the clear width of each recess 9 decreases from the free edge 10 to the bottom 5. The recesses 9 are therefore V-shaped and expediently have a straight section in the apex region. Starting from the apex region of each V-shaped recess 9, narrow, web-shaped and radially extending depressions 16 can be formed, which are assigned to the segment division and extend in the direction of the center of the bottom 5 on its inner surface 7. The advantage of these recesses 9 and, if appropriate, the recesses 16 will be explained later. The shaping of the recesses 9 and, if appropriate, the narrow, radially extending depressions 16 can also be carried out with all other shaping processes in one working step, so that, starting from the body shown in FIG. 2, the pot-shaped blank 3 shown in FIG receives the commutator.

In a next step, there is a further forming process to a base body 12 shown in FIG. 4, which is an intermediate product made of a conductive material in the manufacture of the commutator. This base body 12 has outer anchoring elements 13 obtained by cold forming, which are formed in the vicinity of the free edge 10 of the jacket 4, pointing radially inward. At the same time, if a solid material disc according to the raw material 1 according to FIG. 1 is assumed, a central opening 14 in the base 5 of the pot-shaped blank 3 can be punched out. This central opening 14 is located in the base 5 radially within the ring-shaped arrangement of inner anchoring elements 6. In this treatment step, the inner anchoring elements 6 are preferably also bent slightly radially outward in order to improve their anchoring effect.

Although in the example according to the invention, starting from the body shown in FIG. 3, the base body 12 is reshaped and shaped as an intermediate product in the manufacture of the commutator, the machining operations can of course also be carried out individually in succession. If one starts from a raw material (not shown) which already has a central opening 14 ', the punching process according to FIG. 4 can of course be omitted. The central opening 14 shown there is then already present, which is intended for receiving a rotor shaft of an electrical machine, not shown.

Starting from this base body 12 according to FIG. 4 made of conductive material, which is obtained exclusively by material forming, the commutator can then be completely finished by filling and pressing insulating material into the interior of the pot-shaped blank 3, which is pressed with the help of the inner one Anchoring elements 6 and the outer anchoring elements 13 on the base body 12 is reliably anchored. If necessary, tinning can be carried out. Starting from the flat, continuous outer surface 15 of the base 5, cuts are then made on the commutator to separate and subdivide the segments, only one depth of cut being required, approximately the material thickness of the base 5 is because, for the separation of the segments, the recesses 9 have already been formed on the segment dividing lines on the cylindrical jacket 4. This considerably simplifies the subsequent cutting processing. If the narrow, radially extending depressions 16 are additionally formed, the depth of cut can be reduced even further, so that it is even smaller than the basic material thickness of the base 5. In addition, guidance in cutting processing for segment division and separation can be achieved.

Such a commutator, not shown in more detail, is then provided with electrical lines on the preferably tab-shaped connection elements 2, which are wound, for example, around the connection elements in one or more turns. Then the connecting elements 2 are bent back in the direction of the outer surface of the cylindrical shell 4. This bending process can be carried out easily and without cracks, since the connecting elements 2 are in a ductile or bendable state with an undisturbed fiber course, thanks to the production method according to the invention. A commutator finished in this way is then installed, for example, in an electrical machine.

Since these further processing steps, such as introducing the insulating material filling, cutting the segments, attaching the lead wires and bending the connection elements 2, are common in this field, they are only explained and not shown in detail. Furthermore, they are not the subject of the manufacturing process according to the invention.

Although the manufacture of a base body 12 serving as an intermediate product for a commutator, especially for a flat commutator, has been explained above, the step, which is particularly important according to the invention, can of course also be used for commutators of different types in process engineering be realized in accordance with the first connecting elements 2 are formed from the raw material by material displacement, which already have their finished contour and size after the shaping, and in particular in the ductile finished state. All other forming operations can be selected in a coordinated manner depending on the shape and size of the commutator to be manufactured. Furthermore, it is essential that the base body 12 to be filled with insulating material is produced exclusively by forming operations from a raw material made of conductive material, and that all of these forming operations can be carried out with as few work steps as possible, in a more targeted manner Apart from the connection elements 2, the material consolidation brought about in the cold forming is used to increase the strength of the base body 12. In the case of a flat commutator, in particular the outer surface 15 of the base 5 should be resistant, since the brushes of an electrical machine run on it, for example.

In particular, in the method according to the invention, the connecting elements 2 can be formed in a material-saving manner, since they are shaped directly in finished shape and size without the need for an annular flange on the free edge 10 of the cylindrical jacket 4 of the pot-shaped blank 3. This material reduction due to the avoidance of waste material in the production of the connection elements 2 also allows the material costs to be used for the production of such a commutator to be reduced in order to increase the overall economy of the production method according to the invention. Reference list

1 raw material

2 connection elements

3 blank according to FIG. 3

4 coat

5 floor planner

6 inner anchoring elements

7 inner surface of the floor

9 recess

10 Free edge of the jacket

12 basic body according to FIG. 4

13 External anchoring elements

14 Central opening

14 'Central prefabricated opening in Figure 1

15 outer surface of the floor 5

16 narrow depressions

REPLACEMENT BUTT (RULE 26)

Claims

Process for the production of a commutator

1. A method for producing a commutator, in particular a flat commutator, for electrical machines, which consists of an essentially unprocessed raw material made of conductive material to form a plurality of segments which are insulated and insulated from one another and have associated connecting elements which project radially from the segments individually (2 ), characterized in that the individual connecting elements (2) with finished contour and size as well as with a ductile finished state are first formed directly from the raw material (1) by material displacement.

2. The method according to claim 1, characterized in that prior to the forming to form the connecting elements (2), the raw material (1) is heated depending on the material to avoid any significant deformation material hardening.

3. The method according to claim 2, characterized in that the connecting elements (2) in the heated state of the raw material (1) are formed (half-hot presses).

4. The method according to claim 2 or 3, characterized in that the raw material (1) is heated to a temperature of about 150 ^β C and higher.

5. The method according to claim 4, characterized in that the raw material (1) is heated to a temperature in a range from about 300 to about 700 ^β C.

6. The method according to claim 1 or 2, characterized in that the raw material (1) is annealed before forming to form the connecting elements (2), the connecting elements (2) are formed by cold forming and then annealed again.

7. The method according to any one of the preceding claims, characterized in that after the formation of the individual connection elements (2) by cold forming a cup-shaped blank (3) with an essentially cylindrical jacket

(4) and a substantially flat bottom (5) is formed.

8. The method according to claim 7, characterized in that arranged in a ring shape, on the inner surface (7) of the bottom

(5) substantially axially extending inner anchoring elements (6) for the insulating material filling are formed by cold forming.

9. The method according to claim 7 or 8, characterized in that the segment division associated recesses (9) are formed starting from the free edge (10) of the jacket (4) by material displacement by cold forming.

10. The method according to claim 9, characterized in that the recesses (9) close to the inner surface (7) of the bottom (5) of the cup-shaped blank (3).

11. The method according to claim 9 or 10, characterized in that the clear width of each recess (9) starting from the free edge (10) of the jacket (4) in the direction of the bottom (5) is smaller.

12. The method according to claim 11, characterized in that each recess (9) is approximately V-shaped.

13. The method according to any one of claims 9 to 12, characterized in that on the inner surface (7) of the bottom (5) associated with the segment division, narrow recesses (16) are formed, which radially in the direction of the center of the bottom (5th ) run.

14. The method according to any one of claims 7 to 13, characterized in that the cold forming operations are carried out in one work step.

15. The method according to any one of claims 7 to 14, characterized in that from the jacket (4) radially inwardly facing, outer anchoring elements (13) for the Isolier¬ material filling are formed by cold forming.

16. The method according to any one of claims 7 to 15, characterized in that a central opening (14) is punched out for the rotor shaft of the electrical machines in the bottom (5) of the cup-shaped blank (3).

17. The method according to any one of claims 7 to 16, characterized in that the inner anchoring elements (6) are bent slightly radially outwards.

18. The method according to any one of claims 15 to 17, characterized in that the processing operations are carried out in one work step.