A METHOD OF MANUFACTURING COMMUTATORS

Abstract: A commutator is manufactured by transversaly machining an elongate or cylindrical copper member on one side thereof for providing anchoring elements, whereafter the copper member as cylindrically rolled up is connected with a cast commutator body and is transversely cut for the mutual separation of the commutator elements. The anchoring elements are provided by subjecting the copper member to a plough up action from an undercut sticking and ploughing tool or tool set, whereby raised ribs are produced along the sides of the tool. With this production method the anchor ribs as constituted by compression displaced copper will show a high strength, whereby the method is applicable for the manufacturing of commutators even for high performance requirements.

Description: A method of manufacturing commutators The present invention relates to a method of manufacturing commutators of the type comprising a row of mutually separated commutator elements having an exposed commutator side and an opposite side shaped with integral undercut protruding portions forming anchoring elements, which are secured to a cast commutator body. In traditional commutator production the commutator elements as loose members are laid into a mounting ring to form a cylindrical row of elements, whereafter the assembly is further processed by being provided with the cast commutator body and then cut for the mutual separation of the commutator elements. The mounting of the loose commutator elements is a time consuming work, which has proved difficult to automatize, but the achievable quality.of the commutators produced in this manner is very high primarily due to the fact that the anchoring elements may show a high degree of rigidity or stability, when they are formed - in any of several possible manners - on the single commutator elements, these elements basically being cut from a profiled rod of a suitable material, normally copper. Many attempts have been made to facilitate the production of the commutators, especially for avoiding the handling of the loose commutator elements. Thus, it has been a natural tendency to make use of a unitary material member shaped as a cylinder or a cylindrically rolled up material strip, which is subjected to some mechanical treatment for the formation of the anchoring elements and later on to the same kind of separation cutting as effected to the traditional row of individual commutator elements. However, the anchoring elements as produced in this manner have not so far been Sλy, WIPO produceable with the same high quality as those appearing on the said individual " commutator elements, and a well known result is that commutators produced in the said facilitated manner have not satisfied the same high performance requirements as achievable by conventionally produced commutators. Generally the said known mechanical treatments for the formation of the anchoring elements have been unapt to produce such elements of sufficiently high rigidity or ductability to withstand high separation forces between the commutator elements and the cast body of the commutator. More specifically, the invention relates to a commutator manufacturing method of the latter type, i.e. a method whereby the row of commutator elements is produced from an elongate unitary meterial member, which is machined on one side for the shaping of the said- anchoring elements and is thereafter, upon being connected or cast together with said cast commutator body, divided into said row of separate commutator elements by way of transverse cuttings between the consecutive anchoring element carrying portions of the material member.and it is the purpose of the invention to provide such " a method, by which the anchoring elements may be produced in a simple manner and so as to show a high strength, thus enabling the produced commutators to be both cheap and of high quality. According to the invention the mechanical anchoring element forming treatment is carried out as specified in the characterizing clause of claim 1, i.e. by a transverse ploughing up action on or in the relevant surface of the material member, whereby oblique anchor rib portions are formed by the displaced material, and these rib portions will be very ductile and strong, because they emanate from a compression action on the material. The preferred material is conventional commutator copper, i.e. practically pure copper, which ςυREA OMPI preserves or even builds up a high strength when subjected to a cold compression deformation, which will here apply also to the root area of the rib portions. When the anchor ribs are produced by means of an undercut sticking and ploughing tool they will be left slanting towards each other, while in a commonly preferred shape of the anchor element two oblique ribs are arranged V-like, i.e. slanting away from each other. However, this is easily achievable by arranging for the ploughing to be carried out at the places where the material member is later on to be cut transversely for the separation of the commutator elements; hereby the anchor ribs of each element will be constituted by the adjacent ribs of two neighboring ploughing areas, and besides the advantage will be obtained that the separation cutting is carried out in an area, from which a part of the material has been removed by the ploughing action, for the formation of the anchor ribs, i.e. the material waste as connected with the separation cutting will be reduced. The ploughing action may be effected in a raised portion of the material member located spaced from the side edges thereof, whereby the resulting commutator elements will be provided with anchoring elements along only a partial length thereof, which is desirable for the longitudinal anchoring of the commutator elements in the cast commutator body. The material member may be a straight profile, which is rolled up subsequent to the ploughing treatment, or it may be a cylindrical member, preferably made as a rolled up profile, which is subjected to the ploughing treatment in its cylindrical shape. The plough up action may be effected stepwise by means of a single tool, or a multiple tool may be used. It is particularly advantageous to use two opposite multiple tools, which are mutually staggered and forced into the material member simultaneously from both edges thereof, thereby the material member will need no rigid holding means, as the forces applied from both sides will neutralize each other. In the following the invention is described in more detail with reference to the accompanying drawing, in which:- Fig. 1 is a perspective view of a material member from which a row of commutator elements is to be made, Fig. 2 is a perspective sectional view of the same member and a tool for providing the anchoring elements. Fig. 3 is a plan vie ' illustrating the action of * the tool shown in Fig. 2, Fig " . 4 is an end view of the material member as rolled into a cylindrical shape. Fig. 5 is a perspective sectional view of a commutator unit comprising the material member of Fig. 4, Fig. 6 is a perspective view of a finished commutator, - Fig. 7 is a perspective view of a cylindrical material member and two multiple tools for providing the anchoring elements, and Fig. 8 is an end view of the cylindrical material member as subjected, to further treatment. The material member shown in Fig. 1 is a copper strip 2, which is profiled, by rolling or otherwise, so as to show a broad base portion 4 and a raised flat portion 6 of reduced width. This strip member, which may be supplied from a supply reel, is advanced stepwise through the working station as illustrated in Figs. 2 and 3, in which the strip 2 is supported by a carrier sole 8 and is subjected to the transverse action of a ploughing tool 10, the active part of which is an undercut plough shear 12, the front end of which is ground so as to form an undercut ploughing point or edge 14, the front point of which is located in the level of the* planar underside of the plough shear 12. ^ ΕE OMPI The tool 10 is forced laterally against the raised material portion 6 with the surface of the plough shear 12 in level with or slightly spaced from the top side of the broad portion 4 of the strip 2. By this operation the tool will cause a furrow 16 (Fig. 3) to be ploughed in the material portion 16, because the copper will get forcibly displaced towards the sides of the tool front 14 and flow upwardly along the undercut sides of the plough shear 12, whereby the furrow 16 will be confined between raised anchoring ribs 18 projecting beyond the top level of the profile portion 6. When the shear 12 has thus ploughed through the entire profile portion 6 the tool 10 is retracted and the material strip 2 is advanced a step corresponding to the desired pitch between the neighboring commutator elements of the fina . l product, whereafter the tool is reactuated. Thus, the strip, member 2 will leave the working station with a length profile as shown to the left in Fig. 3, i.e. with the profile portion 6 converted into a row of V-shaped protrusions 20 forming the anchoring elements of the later commutator elements. Thereafter a length of the prepared strip 2 as corresponding to the circumference of the commutator to be produced is cut off, and this cut off strip is rolled up into a cylindrical member. In Fig. 4 this cylindrical member is designated 24 and its split 26. The split 26 is. located idways between two anchoring protrusions 20. Hereafter the material member may be further processed in conventional manner. At first, a rigid body 28, Fig. 5, is produced by casting in the international space of the cylindrical member 24 ' , and, if applicable, about a central bushing 30, whereby the casting of the body 28 will provide for a strong radial holding engagement between the undercut anchoring elements 20 and the casting material. A corresponding OMPI axial anchoring is obtained in that the body 28 is provided with a width broader than that of the raised profile portion 6, i.e. larger than the length of the anchoring elements 20. Thereafter surface grooves 34 (Fig. 5) are cut in the cylindrical body, whereby the commutator cylinder member 24 is devided into a row of mutually insulated commutator elements, each anchored to the body 28 by means of the associated anchoring portion 20. The end portions of these commutator elements as projecting beyond the end of the cast body 28, as shown in Fig. 6, may be bent to form electrical connecter hooks 36, if desired upon the mutual distance between these hooks being increased by way of cutting a broadened notch between them; it will be understood, however, that a desired distance between these hooks may be provided for in , a simple manner already by the working on the strip member 2, viz. by a stamping out of simple notches in the edge portion as shown to the left in Figs. 1 and 2. There are rather high requirements as to the rigidity of the anchoring portions 20, but it has been found that with the use of the described simple ploughing method these portions may show a remarkable strength, which is equal to or better than obtainable with other production methods. As indicated by dotted lines in Fig. 3 it will be possible to use a ploughing tool having two or even more active ploughing shears 12, whereby the production speed may be increased. By the sticking in of the shearing front edge 14 of the tool into the profile portion 6 the said front end will be liable, due to its inclination, to drive into the profile portion, and for this reason the ploughshear 12 should be mounted on a heavily dimensioned and accurately guided tool carrier 10 (Fig. 2). The said diving effect may be reduced by subjecting the material to two or more successive operations, whereby the ploughing cuttings are effected with increasing depth and/or width. The length profile of the anchoring portions 20 may in a simple manner be varied by a corresponding variation of the cross profile of the portion 6 at the strip member 2, e.g. for the provision of local breaks of the anchoring portions for an improved axial holding thereof in the cast body 28, just as also the cross profile of the anchoring portions 20 may be varied widely all according to the profilation of the ploughing tool or tools. The ploughed up ribs 18 may be further ploughed up, viz. by a subsequent treatment with a ploughing tool as sticking into the sides of the ribs spaced from the bottom surface between the anchoring portions 20. In Fig. 7 it is shown that a profiled material strip 2 is rolled up into a cylinder 40, which is placed between opposed tools 42 and 44, each of these tools comprising a circular row of ploughing tools 10, 12, 14 projecting from rear carrier members 46. In a manner not shown these carrier members are connected with means for urging them towards each other, whereby all the ploughing tools 10,12,' 14 are forced into the internally raised portion 6 of the cylinder 40 to effect the said ploughing action thereon. The ploughing tools 10, 12 of the opposed tool units 42, 44 are circumferent- ially staggered so as to each fit into the space between two opposed tools 10,12 whereby all the relevant anchoring elements 20 are produceable by one operation of the two multiple tools 42 and 44. Due to the equal number of separate tools 10, 12 ^ on these multiple tools the cylindrical member 40 will be influenced by generally equal and oppositely directed 'Sticking forces, whereby the cylindrical member 40 need not be separately supported in the direction of the movements of the multiple tools 42 and 44. The anchor elements 20 may be shaped with any of a wide variety of possible shapes, one example being shown in Fig. 8, either by one step operation of correspondingly shaped tools or by successive operation of different tools. The shape and the size of the anchor elements may be selected according to the requirements and circumstances, e.g. the type of material used (copper, aluminium or other) . The cylindrical member as provided with the anchor elements may be connected with the . insulating commutator body 28 (Fig. 5) either by direct casting out thereof or by insertion into a precost body 28. The cylindrical member 40 (Fig. 7) may be a rolled up strip member 2 or an entirely closed ring member produced in any suitable manner.

Claims: CLAIMS 1. A method of manufacturing commutators of the type comprising a row of mutually separated commutator elements having an exposed commutator side and an opposite side shaped with integral undercut protruding 5 portions forming anchoring elements, which are secured to a cast commutator body, whereby the row of commutator elements is produced from an elongate unitary material member, which is machined on one side for the shaping of the said anchoring elements and is thereafter, upon 0 being connected or cast together with said cast commutator body, divided into said row of separate commutator elements by way of transverse cuttings•between the consecutive anchoring element carrying portion of the material member characterized in that the anchoring 5 elements (20) are produced by subjecting the relevant side of the elongate unitary material member (2,40) to a transverse plough up action by means of undercut sticking tool means (12) causing the surface material of the material member to get locally displaced generally -0 outwardly and upwardly along the opposite sides of the sticking tool means (12), whereby the material thus displaced forms an upstanding, generally oblique rib portion (18) located so as to constitute, together with a corresponding, invertedly oblique neighboring rib 5 portion (18), the anchoring element (20) of ' a commutator element as subsequently formed by said transverse cutting. 2. A method according to claim 1, whereby the transverse plough up action is effected along axes coinciding with the axes of said subsequent transverse 0 cuttings (34) , thereby providing each commutator element with a substantially V-shaped anchor rib (20) as composed by rib portions (18) from respective neighboring plough up areas. ^HE QMPI 3. A method according to claim 1, whereby the material member (2,40) is profiled with one or more raised portions (6) spaced from the side edges of the material member the plough up action being effected substantially solely through this or these raised portions. 4. A method according to claim 1 , whereby the transverse plough up action is effected successively along the elongate material member. 5. A method according to claim 1 , whereby the transverse plough up action is effected by means of two opposite sets of sticking and ploughing tools (42,44) which are forced into the material member from opposite side edges thereof. 6. A method according to claim 1 , whereby the plough up a.ction is effected onto a material member (40) already shaped as an entirely or substantially closed cylindrical member. 7. A method according to claims 5 and 6, whereby the interior side of a cylindrical material member (40) is subjected to said plough up action simultaneously from both sides .thereof by means of respective opposed multi tool sets (42,44) , which are mutually staggered so as to produce all the required " anchoring elements in one operation. 8. A method according to claim 1, whereby the material member is subjected to two or more successive ploughing operations in each ploughing area. O PI

Inventors: HANSEN LEIF, NYENSTAD BJARNE ULRICH GORM, WRANG TORBEN CLAUSEN, HANSEN, LEIF, NYENSTAD, BJARNE, ULRICH, GORM, WRANG, TORBEN, CLAUSEN
Applicants: THRIGE TITAN AS, THRIGE-TITAN A/S
Application year: 1983
Main classification: H01R43
IPC codes: H01R43, H02K13