US20080054708A1 - Method for achieving grain orientation - Google Patents
Method for achieving grain orientation Download PDFInfo
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- US20080054708A1 US20080054708A1 US11/846,207 US84620707A US2008054708A1 US 20080054708 A1 US20080054708 A1 US 20080054708A1 US 84620707 A US84620707 A US 84620707A US 2008054708 A1 US2008054708 A1 US 2008054708A1
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- work product
- hot pressing
- grain orientation
- intermediate work
- cavity
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
- H01R43/12—Manufacture of brushes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
- B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
- C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
- C22C32/0052—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R39/00—Rotary current collectors, distributors or interrupters
- H01R39/02—Details for dynamo electric machines
- H01R39/18—Contacts for co-operation with commutator or slip-ring, e.g. contact brush
- H01R39/24—Laminated contacts; Wire contacts, e.g. metallic brush, carbon fibres
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
- B22F2003/145—Both compacting and sintering simultaneously by warm compacting, below debindering temperature
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49009—Dynamoelectric machine
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49117—Conductor or circuit manufacturing
- Y10T29/49119—Brush
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/4998—Combined manufacture including applying or shaping of fluent material
Definitions
- the present disclosure is directed to systems and methods for brush manufacture and, more particularly, to systems and methods that control grain orientation in components, assemblies and other articles of manufacture.
- Exemplary systems and methods disclosed herein utilize hot pressing techniques to enhance the properties and/or functionalities of brushes and other electrical components.
- a brush In the field of motor design, a brush is provided to interact with, i.e., contact, a rotating commutator. Brushes are typically fabricated from carbon and/or copper-containing powder mixtures and brush design is generally recognized as being critical to the operation and durability of the motor assembly.
- a conventional method for manufacturing a graphite brush is disclosed in Japanese Laid-Open Patent Publication No. 90-51345.
- the brush is manufactured from a mixture of powders including an aluminum abrasive, molybdenum disulfide and tungsten disulfide, each powder consisting of particles having diameters of less than 50 ⁇ m.
- the powders are combined in a solution of adhesives, pulverized and prepared with powders having a diameter 100 ⁇ m.
- the total mixture is then compressed at a pressure of 0.25 tons/cm 2 and fired at a temperature of 700° C.
- U.S. Pat. No. 5,447,681 to Seung et al. discloses a method for manufacturing a metal graphite brush that includes the steps of preparing natural graphite powders, wet-mixing the graphite powders with adhesives, pulverizing the mixed powders to diameters of less than 200 ⁇ m, press-molding the powders under a pressure of 2-3 ton/cm 2 and heating at a temperature 700° C. A lead wire is then attached to the press-molded component.
- the present disclosure is directed to systems and methods for manufacture of electrical components, e.g., brush manufacture, and, more particularly, to systems and methods that enable and/or support advantageous control of grain orientation in manufacture of such components, e.g., brush manufacture.
- Exemplary systems and methods disclosed herein utilize hot pressing techniques to enhance the properties and/or functionalities of brushes and other electrical components, e.g., carbon and/or copper-containing components.
- the disclosed techniques and methodologies have wide ranging applications, including the manufacture and/or fabrication of pressed-to-size brushes that are anisotropic, i.e., brushes that have differing physical properties based on the direction of measurement.
- a powder mixture is initially pressed in a conventional manner to form an intermediate work product.
- the conventional pressing step establishes a grain orientation within the intermediate work product that is perpendicular to the direction of the compression forces applied thereto during the conventional pressing process.
- the conventionally-pressed intermediate work product is further processed by a hot pressing technique, wherein the initial grain orientation of the intermediate work product is maintained while compression forces are applied in the hot pressing step.
- the density of the work piece is further increased, thereby enhancing the durability thereof, e.g., when employed as a brush or other electric component.
- Superior functional properties, such as specific resistivity and strength, are also imparted to the work piece through the disclosed hot pressing technique.
- an advantageous fabrication technique wherein a powder mixture is provided and processed to form a work piece having desirable physical and/or functional properties.
- the contents and percentage composition of the powder mixture are not significant to the disclosed fabrication technique.
- the disclosed fabrication technique may be applied to any mixture/blend, e.g., conventional carbon and/or copper-containing powder mixtures.
- mixtures/blends are routinely employed to fabricate brushes having desired physical properties and functional characteristics, any of which may be employed according to the disclosed fabrication technique.
- Alternative powder mixtures may also be employed.
- the powder mixture is initially subjected to a conventional pressing technique to form an intermediate work product.
- the conventional pressing step establishes a grain orientation within the intermediate work product such that grains are substantially perpendicular to the force vectors applied to the powder mixture.
- the conventional pressing technique is generally followed by finishing steps, e.g., finish grinding and the like.
- the conventionally-pressed intermediate work product is subjected to a hot pressing step wherein the grains of the intermediate work product are maintained regardless of the force vectors associated with the hot pressing process.
- the hot pressing step may be used (i) to impart advantageous surface features to the work piece that are not achievable in conventional pressing techniques, (ii) to capture ancillary members/components, e.g., a lead wire/flex member, in ways not possible with conventional pressing techniques, and/or (iii) to form advantageous multi-layer brush assemblies.
- the disclosed fabrication techniques and methods may be employed to form press-to-fit brush members that are not achievable using conventional compression molding techniques.
- the present disclosure is directed to advantageous electrical components, e.g., brushes and brush assemblies, that are formed, in whole or in part based on the disclosed fabrication techniques.
- the present disclosure provides brushes and brush assemblies that define a first axis, wherein the internal grains of the brush/brush assembly are substantially aligned with the first axis and wherein molded surface features are formed on at least one face that is traversed by such first axis.
- a brush assembly is provided that is characterized by a plurality of distinct conventionally-pressed layers, wherein the layers are bonded to each other and wherein the grains of the individual layers can be controlled independent of each other.
- a plurality of distinct intermediate work pieces are formed by conventional pressing techniques and then introduced to a die for simultaneous hot pressing, thereby forming the desired multi-layer brush assembly.
- Multi-layer brush assemblies have particular applicability in washing machine applications, as is well known to persons skilled in the art.
- FIG. 1 is a schematic depiction of a conventional pressing step according to the present disclosure
- FIGS. 2A-2C are schematic diagrams showing an exemplary hot pressing technique for use in hot pressing an intermediate work piece according to the present disclosure
- FIG. 3 is a schematic illustration of three work pieces (brushes) that are distinguished by the orientation of the grains as they would be defined relative to a commutator;
- FIG. 4 is a plan view of an exemplary brush with flex fabricated according to the advantageous method of the present disclosure
- FIG. 5 is a flow chart illustrating an exemplary fabrication technique according to the present disclosure
- FIG. 6 is a depiction of three individual conventionally pressed components in a side-by-side arrangement.
- FIGS. 7A and 7B are depictions of a multi-layered brush assemblies formed according to the present disclosure.
- Systems and methods for manufacture of electrical components, e.g., brushes, and advantageous electrical components, e.g., brushes/brush assemblies, are provided herein.
- the disclosed systems, methods and articles of manufacture advantageously control grain orientation in the manufacturing process such that advantageous physical and functional properties are imparted thereto.
- the disclosed systems and methods utilize hot pressing techniques to provide enhanced properties and/or functionalities to brushes and other electrical components, e.g., carbon and/or copper-containing systems, and find wide ranging applications, including the manufacture and/or fabrication of pressed-to-size brushes.
- a powder mixture is initially pressed in a conventional manner to form an intermediate work product.
- a conventional pressing step is schematically depicted.
- a substantially axial compression force as represented by opposed arrows F 1 and F 2 , is applied to a powder mixture 10 that is contained within a cavity or die (not pictured).
- application of the compression force causes grains within the mixture to align in a substantially perpendicular orientation.
- Grain alignment is schematically depicted by a series of stacked planar regions 12 a , 12 b , etc.
- the operating conditions for the conventional pressing step may vary according to various process parameters, e.g., powder mixture, equipment capabilities, target geometry, and the like.
- the degree to which work piece density may be increased through conventional pressing techniques is generally restricted due to various processing limitations, e.g., the potential for cracked dies and/or parts sticking to tooling if the press tonnages are increased beyond certain limits.
- the intermediate work product formed through conventional pressing is further processed in an advantageous hot pressing step to enhance the properties thereof and, if desired, to provide beneficial surface features, combine ancillary components (e.g., a lead wire/flex), and/or form advantageous multi-layer articles, e.g., a multi-layer brush assembly.
- the intermediate work piece is thus positioned in a cavity/die that is adapted for hot pressing, as described herein.
- FIGS. 2A-2C the interaction between an exemplary intermediate workpiece and an exemplary cavity/die in a hot pressing step is schematically depicted.
- Individual cavities/dies may be sized/configured so as to receive insets that provide desired geometric properties, surface features and/or accommodate positioning of ancillary component(s) that are to be joined to and/or captured by the work piece, e.g., a lead wire/flex.
- the intermediate work piece may be introduced to the hot pressing cavity/die such that the grains formed in the previously completed, conventional pressing step are substantially aligned with the axis of the die, i.e., parallel to the force vector associated with the hot pressing step, or are substantially perpendicular to the force vector associated with the hot pressing step. In circumstances where the grains are positioned parallel to the hot pressing force vector, there are two degrees of freedom.
- intermediate work piece 20 is introduced to a hot pressing cavity/die 22 that includes a surface treatment geometry 24 formed on a lower face thereof. As clearly seen in FIG.
- the grains of the intermediate work piece 20 are advantageously aligned with force vectors F 3 and F 4 within die/cavity 22 (see force vectors in FIG. 2B ).
- a hot pressing force is applied to intermediate work piece 20 (as shown in FIG. 2B ), typically at an elevated hot pressing temperature, for a hot pressing treatment period sufficient to achieve the desired effect(s) on the intermediate work piece 20 .
- a final work product 30 is formed with an advantageous surface effect 32 formed on the face that was in contact with surface treatment geometry 24 .
- the surface effect 32 takes the form of an arcuate, ridged surface, although the present disclosure is not limited to such exemplary surface effect, as will be readily apparent to persons skilled in the art. Indeed, surface effects may be achieved on the top, bottom and/or side surfaces of the intermediate work piece (and ancillary components may be introduced to the intermediate work piece, e.g., a lead wire) during the hot pressing step disclosed herein.
- three exemplary brushes are schematically depicted to illustrate potential grain orientations.
- the grains are aligned having a circumferential grain orientation, i.e., a “G.C.” orientation.
- the grains are aligned with an axial grain orientation, i.e., a “G.A.” orientation.
- the right-most view illustrates an exemplary brush assembly wherein the grains form/define a tangential grain orientation, i.e., a “G.T.” orientation.
- processing parameters associated with the hot press step may be varied without departing from the spirit or scope of the present disclosure. Processing conditions will depend on such variables as the composition of the intermediate work piece, the desired geometric properties of such work piece at the conclusion of the hot pressing step, and the desired physical/functional properties thereof.
- surface properties may be advantageously established through the disclosed hot pressing technique on the top and/or bottom faces of the G.C. and G.A. brushes that could not be effectively achieved with conventional pressing techniques. While it is possible to machine surface features onto the end faces of a work piece after conventional pressing, it is not possible to form detailed and/or non-planar surface features on the faces of the work piece that are perpendicular to the grain orientation. Moreover, the advantageous fabrication techniques of the present disclosure facilitate the formation of detailed and/or non-planar surface features in the hot pressing step, thereby greatly enhancing the effectiveness, flexibility and utility of electrical component fabrication, e.g., brush fabrication.
- an exemplary brush 40 is depicted that includes an intricate and non-planar surface geometry 42 on a face that is perpendicular to the grain orientation thereof.
- Such non-planar surface geometry 42 which may be termed a “press-to-fit” geometry—is advantageously defined during the hot pressing step by forcing the intermediate work piece (with grains aligned with the force vector) into a mold having the desired geometry.
- a lead wire/flex 44 is advantageously introduced to and captured by brush 40 in an orientation that is perpendicular to the grain orientation of the brush 40 .
- introduction of a lead wire 44 in a perpendicular orientation as shown in FIG. 4 cannot be achieved with conventional pressing techniques.
- FIG. 5 an exemplary flow chart for the disclosed fabrication technique is provided. As shown therein, the process generally involves:
- hot pressing step Operating conditions associated with the hot pressing step will vary depending on a host of factors, e.g., the powder constituents and relative percentages thereof, size and geometry of the intermediate work product, etc.
- the hot pressing step is conducted at temperatures that range from about 125° to 1000° F., at pressures that range from about 4000 to 50,000 psi, and for processing times sufficient to achieve the desired work product design/functionality.
- the density of the work piece is further increased relative to the density achieved by way of a conventional pressing step, thereby enhancing the durability of the work piece, e.g., when employed as a brush/brush assembly.
- Superior functional properties such as specific resistivity/lower resistance and strength are also imparted to the work piece through the disclosed hot pressing technique.
- the final work piece may also demonstrate increased oxidation resistance, longer life and, as noted previously, may feature complicated/advantageous shapes/surface features. Exemplary advantageous results achieved through the fabrication process of the present disclosure are set forth in TABLE 1 herein below. The “control” results are reflected at the left for each physical property, and the results according to the present disclosure are set forth at the right.
- the disclosed fabrication method that involves hot pressing a conventionally-pressed intermediate work product yields a work piece with superior properties, with testing showed excellent improvements in all relevant properties.
- the disclosed fabrication method yielded products with reduced resistance, greater strength, and higher density (which translates to enhanced durability).
- the superior properties imparted through the disclosed fabrication technique are effective across a variety of powder mixtures, and the contents and percentage composition of the such powder mixtures, e.g., carbon and/or copper-containing mixtures, are not significant to the superior results achieved thereby. Indeed, the disclosed fabrication technique may be applied to any carbon and/or copper-containing powder mixture/blend.
- FIGS. 6 and 7A the advantageous utility of the disclosed fabrication technique in forming a multi-layer brush assembly is illustrated.
- three distinct conventionally-pressed intermediate work products 50 , 52 , 54 are shown in a side-by-side position.
- Each of the intermediate work products is characterized by a grain orientation that is independent of the potential line of contact with an adjacent work product. Indeed, one or more of the elements that are positioned in a side-by-side relationship may be devoid of grain orientations.
- a multi-layered brush assembly 60 as shown in FIG. 7A is fabricated.
- An adhesive material may be placed between adjacent intermediate work products, if desired.
- one or more of the layers need not take the form of a pressed work product.
- outer layers 72 , 76 may surround an intermediate layer 74 that takes the form of a tape, powder and/or wafer of a completely different material, to form an advantageous multi-layer assembly 70 .
- the multi-layer brush assemblies of FIGS. 7A and 7B benefit from the attributes of the individual intermediate work products and are particularly useful in high intensity applications, e.g., washing machine motors or the like.
- the present disclosure provides advantageous systems and methods for fabrication of carbon-based members, e.g., brushes, and advantageous articles of manufacture fabricated thereby.
- the disclosed systems, methods and articles of manufacture have been described with reference to exemplary embodiments thereof, the present disclosure is not limited by such exemplary embodiments. Rather, the disclosed systems, methods and articles of manufacture are susceptible to modifications, enhancements and/or variations without departing from the spirit or scope of the present disclosure. Such modifications, enhancements and/or variations are expressly encompassed within the scope of the present invention.
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Abstract
Systems and methods for electrical component, e.g., brush, manufacture are provided that control grain orientation. The systems and methods utilize hot pressing techniques to enhance the properties and functionalities of the electrical components/brushes. An intermediate work product characterized by a grain orientation is initially formed through a conventional pressing technique. The conventionally-pressed intermediates are positioned within a cavity/die with the grain orientation in a predetermined orientation relative to the hot press force to be applied thereto. The hot pressed final product exhibits superior resistivity, strength and apparent density/durability. Surface features may be formed on the face(s) of the final work product during the hot pressing step that cannot be achieved in conventional processing techniques. Advantageous articles of manufacture, e.g., brushes and brush assemblies, are also disclosed.
Description
- 1. Technical Field
- The present disclosure is directed to systems and methods for brush manufacture and, more particularly, to systems and methods that control grain orientation in components, assemblies and other articles of manufacture. Exemplary systems and methods disclosed herein utilize hot pressing techniques to enhance the properties and/or functionalities of brushes and other electrical components.
- 2. Background Art
- In the field of motor design, a brush is provided to interact with, i.e., contact, a rotating commutator. Brushes are typically fabricated from carbon and/or copper-containing powder mixtures and brush design is generally recognized as being critical to the operation and durability of the motor assembly. A conventional method for manufacturing a graphite brush is disclosed in Japanese Laid-Open Patent Publication No. 90-51345. The brush is manufactured from a mixture of powders including an aluminum abrasive, molybdenum disulfide and tungsten disulfide, each powder consisting of particles having diameters of less than 50 μm. The powders are combined in a solution of adhesives, pulverized and prepared with powders having a diameter 100 μm. The total mixture is then compressed at a pressure of 0.25 tons/cm2 and fired at a temperature of 700° C.
- U.S. Pat. No. 5,447,681 to Seung et al. discloses a method for manufacturing a metal graphite brush that includes the steps of preparing natural graphite powders, wet-mixing the graphite powders with adhesives, pulverizing the mixed powders to diameters of less than 200 μm, press-molding the powders under a pressure of 2-3 ton/cm2 and heating at a temperature 700° C. A lead wire is then attached to the press-molded component.
- Despite efforts to date, techniques for fabrication of brushes imposes significant limitations on the design, geometry, structural features and properties/performance. Moreover, brushes and brush assemblies fabricated according to conventional processing techniques/methodologies are characterized by durability issues based, at least in part, on density limitations associated with conventional fabrication techniques. These and other shortcomings and limitations are overcome by the techniques, methods and articles of manufacture disclosed herein.
- The present disclosure is directed to systems and methods for manufacture of electrical components, e.g., brush manufacture, and, more particularly, to systems and methods that enable and/or support advantageous control of grain orientation in manufacture of such components, e.g., brush manufacture. Exemplary systems and methods disclosed herein utilize hot pressing techniques to enhance the properties and/or functionalities of brushes and other electrical components, e.g., carbon and/or copper-containing components. The disclosed techniques and methodologies have wide ranging applications, including the manufacture and/or fabrication of pressed-to-size brushes that are anisotropic, i.e., brushes that have differing physical properties based on the direction of measurement.
- According to exemplary embodiments of the present disclosure, a powder mixture is initially pressed in a conventional manner to form an intermediate work product. The conventional pressing step establishes a grain orientation within the intermediate work product that is perpendicular to the direction of the compression forces applied thereto during the conventional pressing process. Thereafter, the conventionally-pressed intermediate work product is further processed by a hot pressing technique, wherein the initial grain orientation of the intermediate work product is maintained while compression forces are applied in the hot pressing step. Through the hot pressing step, the density of the work piece is further increased, thereby enhancing the durability thereof, e.g., when employed as a brush or other electric component. Superior functional properties, such as specific resistivity and strength, are also imparted to the work piece through the disclosed hot pressing technique.
- Thus, an advantageous fabrication technique is disclosed wherein a powder mixture is provided and processed to form a work piece having desirable physical and/or functional properties. The contents and percentage composition of the powder mixture are not significant to the disclosed fabrication technique. Indeed, the disclosed fabrication technique may be applied to any mixture/blend, e.g., conventional carbon and/or copper-containing powder mixtures. Thus, as is known in the art, different mixtures/blends are routinely employed to fabricate brushes having desired physical properties and functional characteristics, any of which may be employed according to the disclosed fabrication technique. Alternative powder mixtures may also be employed.
- The powder mixture is initially subjected to a conventional pressing technique to form an intermediate work product. The conventional pressing step establishes a grain orientation within the intermediate work product such that grains are substantially perpendicular to the force vectors applied to the powder mixture. According to conventional fabrication techniques, the conventional pressing technique is generally followed by finishing steps, e.g., finish grinding and the like. However, according to the advantageous fabrication technique of the present disclosure, the conventionally-pressed intermediate work product is subjected to a hot pressing step wherein the grains of the intermediate work product are maintained regardless of the force vectors associated with the hot pressing process.
- Through the hot pressing step, the properties of the intermediate work product are enhanced. In addition, the hot pressing step may be used (i) to impart advantageous surface features to the work piece that are not achievable in conventional pressing techniques, (ii) to capture ancillary members/components, e.g., a lead wire/flex member, in ways not possible with conventional pressing techniques, and/or (iii) to form advantageous multi-layer brush assemblies. Indeed, the disclosed fabrication techniques and methods may be employed to form press-to-fit brush members that are not achievable using conventional compression molding techniques.
- In addition to the advantageous fabrication techniques disclosed herein, the present disclosure is directed to advantageous electrical components, e.g., brushes and brush assemblies, that are formed, in whole or in part based on the disclosed fabrication techniques. Thus, the present disclosure provides brushes and brush assemblies that define a first axis, wherein the internal grains of the brush/brush assembly are substantially aligned with the first axis and wherein molded surface features are formed on at least one face that is traversed by such first axis. In a further exemplary embodiment of the present disclosure, a brush assembly is provided that is characterized by a plurality of distinct conventionally-pressed layers, wherein the layers are bonded to each other and wherein the grains of the individual layers can be controlled independent of each other. In exemplary embodiments of the disclosed multi-layer brush assembly, a plurality of distinct intermediate work pieces (e.g., three) are formed by conventional pressing techniques and then introduced to a die for simultaneous hot pressing, thereby forming the desired multi-layer brush assembly. Multi-layer brush assemblies have particular applicability in washing machine applications, as is well known to persons skilled in the art.
- Additional features, functions and advantages of the disclosed fabrication techniques/methods and the articles of manufacture formed thereby will be apparent from the detailed description which follows, particularly when read in conjunction with the appended figures.
- To assist those of ordinary skill in the art in making and using the disclosed fabrication techniques and articles of manufacture, reference is made to the accompanying figures, wherein:
-
FIG. 1 is a schematic depiction of a conventional pressing step according to the present disclosure; -
FIGS. 2A-2C are schematic diagrams showing an exemplary hot pressing technique for use in hot pressing an intermediate work piece according to the present disclosure; -
FIG. 3 is a schematic illustration of three work pieces (brushes) that are distinguished by the orientation of the grains as they would be defined relative to a commutator; -
FIG. 4 is a plan view of an exemplary brush with flex fabricated according to the advantageous method of the present disclosure; -
FIG. 5 is a flow chart illustrating an exemplary fabrication technique according to the present disclosure; -
FIG. 6 is a depiction of three individual conventionally pressed components in a side-by-side arrangement; and -
FIGS. 7A and 7B are depictions of a multi-layered brush assemblies formed according to the present disclosure. - Systems and methods for manufacture of electrical components, e.g., brushes, and advantageous electrical components, e.g., brushes/brush assemblies, are provided herein. The disclosed systems, methods and articles of manufacture advantageously control grain orientation in the manufacturing process such that advantageous physical and functional properties are imparted thereto. The disclosed systems and methods utilize hot pressing techniques to provide enhanced properties and/or functionalities to brushes and other electrical components, e.g., carbon and/or copper-containing systems, and find wide ranging applications, including the manufacture and/or fabrication of pressed-to-size brushes.
- According to exemplary embodiments of the present disclosure, a powder mixture is initially pressed in a conventional manner to form an intermediate work product. With reference to
FIG. 1 , a conventional pressing step is schematically depicted. A substantially axial compression force, as represented by opposed arrows F1 and F2, is applied to apowder mixture 10 that is contained within a cavity or die (not pictured). As schematically depicted inFIG. 1 , application of the compression force causes grains within the mixture to align in a substantially perpendicular orientation. Grain alignment is schematically depicted by a series of stackedplanar regions - The operating conditions for the conventional pressing step may vary according to various process parameters, e.g., powder mixture, equipment capabilities, target geometry, and the like. The degree to which work piece density may be increased through conventional pressing techniques is generally restricted due to various processing limitations, e.g., the potential for cracked dies and/or parts sticking to tooling if the press tonnages are increased beyond certain limits.
- According to the present disclosure, the intermediate work product formed through conventional pressing is further processed in an advantageous hot pressing step to enhance the properties thereof and, if desired, to provide beneficial surface features, combine ancillary components (e.g., a lead wire/flex), and/or form advantageous multi-layer articles, e.g., a multi-layer brush assembly. The intermediate work piece is thus positioned in a cavity/die that is adapted for hot pressing, as described herein. With reference to
FIGS. 2A-2C , the interaction between an exemplary intermediate workpiece and an exemplary cavity/die in a hot pressing step is schematically depicted. Individual cavities/dies may be sized/configured so as to receive insets that provide desired geometric properties, surface features and/or accommodate positioning of ancillary component(s) that are to be joined to and/or captured by the work piece, e.g., a lead wire/flex. - Of note, the intermediate work piece may be introduced to the hot pressing cavity/die such that the grains formed in the previously completed, conventional pressing step are substantially aligned with the axis of the die, i.e., parallel to the force vector associated with the hot pressing step, or are substantially perpendicular to the force vector associated with the hot pressing step. In circumstances where the grains are positioned parallel to the hot pressing force vector, there are two degrees of freedom. Thus, with reference to
FIGS. 2A-2C ,intermediate work piece 20 is introduced to a hot pressing cavity/die 22 that includes a surface treatment geometry 24 formed on a lower face thereof. As clearly seen inFIG. 2A , the grains of theintermediate work piece 20 are advantageously aligned with force vectors F3 and F4 within die/cavity 22 (see force vectors inFIG. 2B ). A hot pressing force is applied to intermediate work piece 20 (as shown inFIG. 2B ), typically at an elevated hot pressing temperature, for a hot pressing treatment period sufficient to achieve the desired effect(s) on theintermediate work piece 20. Afinal work product 30 is formed with anadvantageous surface effect 32 formed on the face that was in contact with surface treatment geometry 24. In the exemplary embodiment ofFIGS. 2A-2C , thesurface effect 32 takes the form of an arcuate, ridged surface, although the present disclosure is not limited to such exemplary surface effect, as will be readily apparent to persons skilled in the art. Indeed, surface effects may be achieved on the top, bottom and/or side surfaces of the intermediate work piece (and ancillary components may be introduced to the intermediate work piece, e.g., a lead wire) during the hot pressing step disclosed herein. - With reference to
FIG. 3 , three exemplary brushes are schematically depicted to illustrate potential grain orientations. In the left-most view, the grains are aligned having a circumferential grain orientation, i.e., a “G.C.” orientation. In the middle view, the grains are aligned with an axial grain orientation, i.e., a “G.A.” orientation. Finally, the right-most view illustrates an exemplary brush assembly wherein the grains form/define a tangential grain orientation, i.e., a “G.T.” orientation. - As with the conventional pressing step discussed above, the processing parameters associated with the hot press step may be varied without departing from the spirit or scope of the present disclosure. Processing conditions will depend on such variables as the composition of the intermediate work piece, the desired geometric properties of such work piece at the conclusion of the hot pressing step, and the desired physical/functional properties thereof.
- With further reference to
FIG. 3 , it is noted that surface properties may be advantageously established through the disclosed hot pressing technique on the top and/or bottom faces of the G.C. and G.A. brushes that could not be effectively achieved with conventional pressing techniques. While it is possible to machine surface features onto the end faces of a work piece after conventional pressing, it is not possible to form detailed and/or non-planar surface features on the faces of the work piece that are perpendicular to the grain orientation. Moreover, the advantageous fabrication techniques of the present disclosure facilitate the formation of detailed and/or non-planar surface features in the hot pressing step, thereby greatly enhancing the effectiveness, flexibility and utility of electrical component fabrication, e.g., brush fabrication. - With reference to
FIG. 4 , anexemplary brush 40 is depicted that includes an intricate andnon-planar surface geometry 42 on a face that is perpendicular to the grain orientation thereof. Suchnon-planar surface geometry 42—which may be termed a “press-to-fit” geometry—is advantageously defined during the hot pressing step by forcing the intermediate work piece (with grains aligned with the force vector) into a mold having the desired geometry. In addition, a lead wire/flex 44 is advantageously introduced to and captured bybrush 40 in an orientation that is perpendicular to the grain orientation of thebrush 40. As withnon-planar surface geometry 42, introduction of alead wire 44 in a perpendicular orientation as shown inFIG. 4 cannot be achieved with conventional pressing techniques. - With reference to
FIG. 5 , an exemplary flow chart for the disclosed fabrication technique is provided. As shown therein, the process generally involves: -
- 1. Providing a powder mixture having desired blend characteristics, e.g., a carbon and/or copper-based powder mixture;
- 2. Conventionally pressing the powder mixture to form an intermediate work product; and
- 3. Hot pressing the intermediate work product to form a final work product.
- Operating conditions associated with the hot pressing step will vary depending on a host of factors, e.g., the powder constituents and relative percentages thereof, size and geometry of the intermediate work product, etc. Generally, the hot pressing step is conducted at temperatures that range from about 125° to 1000° F., at pressures that range from about 4000 to 50,000 psi, and for processing times sufficient to achieve the desired work product design/functionality.
- Through the hot pressing step, the density of the work piece is further increased relative to the density achieved by way of a conventional pressing step, thereby enhancing the durability of the work piece, e.g., when employed as a brush/brush assembly. Superior functional properties such as specific resistivity/lower resistance and strength are also imparted to the work piece through the disclosed hot pressing technique. The final work piece may also demonstrate increased oxidation resistance, longer life and, as noted previously, may feature complicated/advantageous shapes/surface features. Exemplary advantageous results achieved through the fabrication process of the present disclosure are set forth in TABLE 1 herein below. The “control” results are reflected at the left for each physical property, and the results according to the present disclosure are set forth at the right.
- As shown above, the disclosed fabrication method that involves hot pressing a conventionally-pressed intermediate work product yields a work piece with superior properties, with testing showed excellent improvements in all relevant properties. The disclosed fabrication method yielded products with reduced resistance, greater strength, and higher density (which translates to enhanced durability). The superior properties imparted through the disclosed fabrication technique are effective across a variety of powder mixtures, and the contents and percentage composition of the such powder mixtures, e.g., carbon and/or copper-containing mixtures, are not significant to the superior results achieved thereby. Indeed, the disclosed fabrication technique may be applied to any carbon and/or copper-containing powder mixture/blend.
- With reference to
FIGS. 6 and 7A , the advantageous utility of the disclosed fabrication technique in forming a multi-layer brush assembly is illustrated. InFIG. 6 , three distinct conventionally-pressedintermediate work products multi-layered brush assembly 60 as shown inFIG. 7A is fabricated. An adhesive material may be placed between adjacent intermediate work products, if desired. - Of note, in exemplary embodiments of the present disclosure, one or more of the layers need not take the form of a pressed work product. For example, as shown in
FIG. 7B ,outer layers intermediate layer 74 that takes the form of a tape, powder and/or wafer of a completely different material, to form an advantageousmulti-layer assembly 70. The multi-layer brush assemblies ofFIGS. 7A and 7B benefit from the attributes of the individual intermediate work products and are particularly useful in high intensity applications, e.g., washing machine motors or the like. - Thus, the present disclosure provides advantageous systems and methods for fabrication of carbon-based members, e.g., brushes, and advantageous articles of manufacture fabricated thereby. Although the disclosed systems, methods and articles of manufacture have been described with reference to exemplary embodiments thereof, the present disclosure is not limited by such exemplary embodiments. Rather, the disclosed systems, methods and articles of manufacture are susceptible to modifications, enhancements and/or variations without departing from the spirit or scope of the present disclosure. Such modifications, enhancements and/or variations are expressly encompassed within the scope of the present invention.
Claims (20)
1. A method for fabricating a work piece, comprising:
a. providing a powder mixture;
b. pressing the powder mixture to form an intermediate work product characterized by a grain orientation that is perpendicular to an axis defined by force application during said pressing;
c. orienting the intermediate work product in a cavity with the grain orientation in a predetermined alignment relative to a force axis to be applied to the cavity; and
d. hot pressing the intermediate work product to form a final work product.
2. A method according to claim 1 , wherein the powder mixture includes at least one of carbon and copper.
3. A method according to claim 1 , wherein the intermediate work product is characterized by a specific resistivity, break strength and apparent density.
4. A method according to claim 3 , wherein the final work product is characterized by (i) a specific resistivity that is less than the specific resistivity of the intermediate work product; (ii) a break strength that is greater than the break strength of the intermediate work product; and (iii) an apparent density that is greater than the apparent density of the intermediate work product.
5. A method according to claim 1 , wherein the intermediate work product is oriented in the hot pressed cavity such that the grain orientation is independent of the force axis.
6. A method according to claim 5 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a circumferential or axial grain orientation after hot pressing.
7. A method according to claim 1 , wherein the intermediate work product is oriented in the cavity such that the grain orientation defines a tangential grain orientation after hot pressing.
8. A method according to claim 1 , further comprising positioning an ancillary component to be joined to the intermediate work product during hot pressing.
9. A method according to claim 8 , wherein the ancillary component is a lead wire.
10. A method according to claim 1 , further comprising positioning a plurality of intermediate work products in the cavity in side-by-side relation prior to hot pressing.
11. A method according to claim 10 , wherein the final work product is a multi-layer brush assembly.
12. A method according to claim 1 , wherein the cavity is adapted to form at least one surface feature on a face of the final work product during hot pressing.
13. A method according to claim 12 , wherein the at least one surface feature is formed on an end face of the final work product and is non-planar.
14. A final work product fabricated according to the method of claim 1 .
15. (canceled)
16. (canceled)
17. (canceled)
18. (canceled)
19. (canceled)
20. (canceled)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/846,207 US20080054708A1 (en) | 2006-09-01 | 2007-08-28 | Method for achieving grain orientation |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/515,467 US7498712B2 (en) | 2006-09-01 | 2006-09-01 | Grain orientation control through hot pressing techniques |
US11/846,207 US20080054708A1 (en) | 2006-09-01 | 2007-08-28 | Method for achieving grain orientation |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/515,467 Division US7498712B2 (en) | 2006-09-01 | 2006-09-01 | Grain orientation control through hot pressing techniques |
Publications (1)
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US20080054708A1 true US20080054708A1 (en) | 2008-03-06 |
Family
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US11/515,467 Expired - Fee Related US7498712B2 (en) | 2006-09-01 | 2006-09-01 | Grain orientation control through hot pressing techniques |
US11/846,207 Abandoned US20080054708A1 (en) | 2006-09-01 | 2007-08-28 | Method for achieving grain orientation |
US11/846,262 Abandoned US20080086875A1 (en) | 2006-09-01 | 2007-08-28 | Grain orientation control through hot pressing techniques |
Family Applications Before (1)
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US11/515,467 Expired - Fee Related US7498712B2 (en) | 2006-09-01 | 2006-09-01 | Grain orientation control through hot pressing techniques |
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US11/846,262 Abandoned US20080086875A1 (en) | 2006-09-01 | 2007-08-28 | Grain orientation control through hot pressing techniques |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102008001702A1 (en) * | 2008-05-09 | 2009-11-12 | Robert Bosch Gmbh | Electric machine, in particular commutator machine |
EP3501694A1 (en) * | 2017-12-21 | 2019-06-26 | HIPtec AS | A method for manufacturing a metal based component having a cavity, and a metal based component having a cavity |
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- 2007-08-28 US US11/846,207 patent/US20080054708A1/en not_active Abandoned
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Also Published As
Publication number | Publication date |
---|---|
WO2008027905A3 (en) | 2008-09-18 |
WO2008027905A2 (en) | 2008-03-06 |
US20080054753A1 (en) | 2008-03-06 |
US20080086875A1 (en) | 2008-04-17 |
US7498712B2 (en) | 2009-03-03 |
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