US3849878A - Method of making resistance element - Google Patents

Method of making resistance element Download PDF

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Publication number
US3849878A
US3849878A US00311555A US31155572A US3849878A US 3849878 A US3849878 A US 3849878A US 00311555 A US00311555 A US 00311555A US 31155572 A US31155572 A US 31155572A US 3849878 A US3849878 A US 3849878A
Authority
US
United States
Prior art keywords
cores
wire
wound
resistance
resistance elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00311555A
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English (en)
Inventor
F Rudd
G Mackenzie
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northrop Grumman Space and Mission Systems Corp
Original Assignee
TRW Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by TRW Inc filed Critical TRW Inc
Priority to US00311555A priority Critical patent/US3849878A/en
Priority to AU59656/73A priority patent/AU475049B2/en
Priority to JP48105127A priority patent/JPS4986848A/ja
Priority to CA181,978A priority patent/CA1002625A/en
Priority to IT69859/73A priority patent/IT996755B/it
Priority to FR7335238A priority patent/FR2209185B1/fr
Priority to GB5247573A priority patent/GB1443758A/en
Priority to SE7315693A priority patent/SE388304B/xx
Priority to DE2360385A priority patent/DE2360385A1/de
Application granted granted Critical
Publication of US3849878A publication Critical patent/US3849878A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • 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
    • Y10T29/49082—Resistor making
    • 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
    • Y10T29/49789—Obtaining plural product pieces from unitary workpiece
    • 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
    • Y10T29/49789—Obtaining plural product pieces from unitary workpiece
    • Y10T29/49798—Dividing sequentially from leading end, e.g., by cutting or breaking
    • 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
    • Y10T29/4981—Utilizing transitory attached element or associated separate material
    • 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
    • Y10T29/4981—Utilizing transitory attached element or associated separate material
    • Y10T29/49812—Temporary protective coating, impregnation, or cast layer

Definitions

  • a method of makingwire wound electrical resistance elements comprising the steps of winding a respective resistance wire helieally around and along each of a plurality of elongated wire cores which cores are coated with an insulating material, coating each of said wound cores with a protective layer, arranging said wound cores in closely spaced parallel relation, encapsulating said arranged wire cores in a block of plasticmaterial, cutting through the block and the wound cores at longitudinally spaced 'points along planes perpendicular to the longitudinal axes of the wound cores to form a plurality of wafers each of which contains a plurality of resistance elements;and then separating said resistance elements from the plastic of the respective wafers.
  • the disclosure also includes the steps in which prior to separating resistance elements from the plastic of the wafer, the ends of the wire cores are contacted with an etchant to etch away a portion of the ends of the wire cores, after which the erfds are coated with a film of an insulating material.
  • the present invention relates to an electrical resistance element and a method of making the same. More particularly, the present invention relates to a wire wound resistance element for a potentiometer and a batch method for making the resistance elements.
  • the wire wound resistance elements used in potentiometers in general comprise a core having an electrical resistance wire helically wound around the core.
  • One type of core used is a magnet wire, such as copper, having a coating of an insulating material thereover to insulate the resistance wire from the core wire.
  • the resistance wire is generally coated with a strip of an insulating material to hold the turns of the resistance wire in place on the core.
  • These resistance elements are generally made by winding the resistance wire on an elongated length of the core.
  • the insulating strip is then coated and cured on the wound core.
  • the wound core is then cut into the desired lengths for the potentiometer elements, generally with a metal saw. This method has a number of disadvantages.
  • the sawing with a metal saw results in unwinding the resistance wire at the ends of the elements and a smearing of the resistance wire across the ends of the metal core.
  • the unraveled and smeared ends of the resistance wire must be removed by hand labor using tweezers. This slows down the operation and adds considerably to the cost of making the elements.
  • the insulating strips coated on the wound core tend to creep onto the wiper track area of the element during the application of the strip and could ruin the element.
  • All of the resistance elements in a wafer are treated simultaneously to space the ends of the wire cores from the ends of the insulating layer thereon and to provide an insulating film on the ends of the wire cores. The resistance elements are then separated from the plastic of the wafers.
  • FIG. 1 is a side elevation view, partially sectioned, of the wire wound resistance element of the present invention. 7
  • FIG. 2 is an enlarged perspective view of a portion of an elongated wire wound and coated core from which the resistance elements of the present invention are made and illustrates the first step in the method of the present invention.
  • FIGS. 3 7 are perspective views illustrating the various steps of the method of the present invention.
  • Resistance element 10 comprises a magnet wire core 12, such as of a copper wire, having a layer 14 of an electrical insulating material, such as a polyimide resin, coated on the surface thereof.
  • the insulating layer 14 extends beyond both ends of the core 12.
  • An electrical resistance wire 16 is helically wound around the insulating layer 14 along the entire length of the insulatinglayer 14.
  • a protection layer 18 of an electrical insulating material, such as a polyimide or epoxy resin, is coated over the resistance wire winding 16.
  • the protection layer 18 has a narrow opening 20 therethrough which extends longitudinally along the entire length of the resistance element 10.
  • the opening 20 exposes a portion of the resistance wire winding 16 to provide a track along which a movable contact of a potentiometer .can make contact with the resistance wire winding.
  • a thin film 22 of an electrical insulating material, such as apolymide or epoxy resin, is coated over each end of the core 12.
  • Each of the insulating films 22 extends across a respective end of the insulating layer 14 and onto the surface of the protection layer 18.
  • resistance element 10 To make resistance element 10, according to the method of the present invention, one starts with an elongated length of the magnet wire core 12 having the layer 14 of the electrical insulating material thereon.
  • the resistance wire 16 is helically wound around the elongated length of the insulated core 12 along the entire length of the core.
  • the protection layer 18 is then applied to the wound core, such as by spraying, painting, or dipping.
  • the protection layer 18 is then partially cured by a short heating cycle.
  • a polyimide resin protection layer can be partially cured by heating at a temperature of 200C to 225C for 5 to 15 minutes.
  • FIG. 2 is an enlarged view showing an end portion of an elongated length 24 ofthe resistance wire wound core with the protection layer 18 thereon.
  • the narrow longitudinal opening 20 is then formed in the protection layer 18 along the entire length of the core so as to expose a portion of the resistance wire. This can be achieved either by buffing the protection layer 18 with a narrow abrasive impregnated rubber belt or by a blast of bicarbonate soda powder.
  • the elongated length 24 of the wound core is thencleaned and the protection layer 18 fully cured.
  • the elongated length 24 can be cleaned by ultrasonic cleaning in freon MT or with methylene chloride or a detergent followed by ultrasonic cleaning in freon MT.
  • the polyimide protection layer 18 can be then fully cured by heating at 200C for l to 4 hours.
  • a plurality of the length 24 of the wound cores are then encased in a block 26 of a plastic material as shown in FIG. 3.
  • the plastic material of the block 26 is one which is relatively inexpensive and which is controllably soluble in a solvent which does not attack the material of the lengths 24 of the wound cores.
  • Polyester resins have been found suitable for this purpose. However, epoxy, polyurethane, silicone and thermoplastic resins as well as such waxes as candle wax are also usable depending on the material used for the protection layers 18 and the insulating layers 14 of the wound cores.
  • the material of the block 26 is also preferably filled with particles of a mineral, such as mica, glass beads or silica. As many as 100 length 24 of the wound cores can be included in the block 26.
  • the block 26 is then cut completely through at uniformly spaced points along its length, along parallel planes which are perpendicular to the longitudinal axes of the lengths 24 of the wound cores.
  • the cuts can be made with any suitable tool, such as a rotating circular diamond saw.
  • the cuts are spaced apart a distance equal to the desired length of the resistance elements being produced, typically V2 to inch.
  • the block 26 is divided into a plurality of wafers 28 with each wafer containing a plurality of lengths 24' for producing the resistance elements 10.
  • the exposed ends of the wire cores 12, at each end surface of each wafer 28, is contacted with an etchant to etch away a portion of the ends of the wire cores 12 as shown in FIG. 5.
  • a suitable etchant may be ammonium persulfate, nitric acid or ferric chloride. As shown in FIG. 5, this leaves the ends of the insulating layers 14 projecting beyond the ends of the wire cores 12.
  • the wafer 28 is washed and rinsed in water for removing residual etchant. Each wafer 28 is then immersed in a suitable solvent for a period of time necessary to dissolve or soften the plastic material at the surfaces of the wafers 28.
  • the solvent is one which will slowly dissolve the particular plastic being used, but does not attack the materials of the wound cores.
  • the plastic is a polyester resin
  • methylene chloride has been found to be a satisfactory solvent.
  • Chlorinated solvents can be used for epoxy and silicon resins, alcohols or ketones for polyurethane, and various hydrocarbon solvents for waxes.
  • the amount of the protection layers 18 which are exposed will depend on the length of time that the wafers 28 are immersed in the solvent. For example, using methylene chloride as a solvent for a polyester resin, leaving the wafers 28 in the solvent for approximately 10 minutes will dissolve sufficient amount of the plastic to expose approximately 10 mils of the protection layer 18 at each end of each of the lengths 24'.
  • a thin film 22 of an heating As shown in FIG. 7, a thin film 22 of an heating.
  • the material is coated on each end of each of the wire cores 12 with the film extending over the exposed dissolved so of the protection layer 18.
  • the insulating material films 22 are cured by heating
  • the wafers 28 are then immersed inthe solvent bath and left in the solvent until all of the plastic is dissolvedso as to separate the individual lengths 24 in the wafers. After the plastic is completely dissolved, the lengths 24' proving the individual resistance elements 10 are removed from the solvent and washed to remove the solvent. The resistance elements 10 are then ready to be used in potentiometer assemblies.
  • the method of the present invention has been described with regard to making straight resistance elements 10, it can also be used to make resistance elements which are in the form of a helix.
  • the elongated wound cores 24 are wound in a helix and a plurality of the helically wound cores 24 are molded in a plastic block 26. The block is then handled in the same manner as previously described.
  • the insulating film on each end of the wound core insulates the wire core so as to prevent the resistance wire from shorting across the ends of the wire core
  • the method of the present invention provides for the mass production of the resistance elements 10 with greater ease of handling the resistance elements, with greater speed, at a lower cost per resistance element and with uniformity of size. Also, it provides a resistance element in which the resistance wire is firmly held in place on the core and will not short out across the ends of the wire core.
  • a method of making electrical resistance elements comprising the steps of winding a respective resistance wire helically around and along each of a plurality of elongated wire cores which cores are coated with an insulating ma terial,

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Apparatuses And Processes For Manufacturing Resistors (AREA)
US00311555A 1972-12-04 1972-12-04 Method of making resistance element Expired - Lifetime US3849878A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
US00311555A US3849878A (en) 1972-12-04 1972-12-04 Method of making resistance element
AU59656/73A AU475049B2 (en) 1972-12-04 1973-08-27 Resistance element and method of making the same
JP48105127A JPS4986848A (enrdf_load_stackoverflow) 1972-12-04 1973-09-19
CA181,978A CA1002625A (en) 1972-12-04 1973-09-26 Wire wound resistance element and method
IT69859/73A IT996755B (it) 1972-12-04 1973-09-27 Resistenza per potenziometro e procedimento per la sua fabbricazio ne
FR7335238A FR2209185B1 (enrdf_load_stackoverflow) 1972-12-04 1973-10-02
GB5247573A GB1443758A (en) 1972-12-04 1973-11-12 Resistance element and method of making the same
SE7315693A SE388304B (sv) 1972-12-04 1973-11-20 Motstandselement samt sett att framstella motstandselement
DE2360385A DE2360385A1 (de) 1972-12-04 1973-12-04 Widerstandselement und verfahren zu seiner herstellung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00311555A US3849878A (en) 1972-12-04 1972-12-04 Method of making resistance element

Publications (1)

Publication Number Publication Date
US3849878A true US3849878A (en) 1974-11-26

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ID=23207431

Family Applications (1)

Application Number Title Priority Date Filing Date
US00311555A Expired - Lifetime US3849878A (en) 1972-12-04 1972-12-04 Method of making resistance element

Country Status (9)

Country Link
US (1) US3849878A (enrdf_load_stackoverflow)
JP (1) JPS4986848A (enrdf_load_stackoverflow)
AU (1) AU475049B2 (enrdf_load_stackoverflow)
CA (1) CA1002625A (enrdf_load_stackoverflow)
DE (1) DE2360385A1 (enrdf_load_stackoverflow)
FR (1) FR2209185B1 (enrdf_load_stackoverflow)
GB (1) GB1443758A (enrdf_load_stackoverflow)
IT (1) IT996755B (enrdf_load_stackoverflow)
SE (1) SE388304B (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268946A (en) * 1977-06-08 1981-05-26 Owens-Corning Fiberglas Corporation Method for finishing a plate
US4481082A (en) * 1982-11-10 1984-11-06 Martin Marietta Corporation Method of making rings
US4801912A (en) * 1985-06-07 1989-01-31 American Precision Industries Inc. Surface mountable electronic device
US5027101A (en) * 1987-01-22 1991-06-25 Morrill Jr Vaughan Sub-miniature fuse
US5040284A (en) * 1987-01-22 1991-08-20 Morrill Glasstek Method of making a sub-miniature electrical component, particularly a fuse
US5097245A (en) * 1987-01-22 1992-03-17 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5122774A (en) * 1987-01-22 1992-06-16 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5131137A (en) * 1987-01-22 1992-07-21 Morrill Glasstek, Inc. Method of making a sub-miniature electrical component particularly a fuse
US5155462A (en) * 1987-01-22 1992-10-13 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5224261A (en) * 1987-01-22 1993-07-06 Morrill Glasstek, Inc. Method of making a sub-miniature electrical component, particularly a fuse
US6973711B1 (en) * 2000-05-24 2005-12-13 Fonar Corporation Method for making pieces for a magnetic resonance imaging magnet
TWI666819B (zh) * 2016-12-19 2019-07-21 美商雷森公司 用於製造一複合基板循環器組件及複合基板循環器組件前體之方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3252205A (en) * 1963-02-11 1966-05-24 Gen Dynamics Corp Thermoelectric units
US3358362A (en) * 1965-01-21 1967-12-19 Int Resistance Co Method of making an electrical resistor

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3205467A (en) * 1962-07-27 1965-09-07 Ward Leonard Electric Co Plastic encapsulated resistor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3252205A (en) * 1963-02-11 1966-05-24 Gen Dynamics Corp Thermoelectric units
US3358362A (en) * 1965-01-21 1967-12-19 Int Resistance Co Method of making an electrical resistor

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4268946A (en) * 1977-06-08 1981-05-26 Owens-Corning Fiberglas Corporation Method for finishing a plate
US4481082A (en) * 1982-11-10 1984-11-06 Martin Marietta Corporation Method of making rings
US4801912A (en) * 1985-06-07 1989-01-31 American Precision Industries Inc. Surface mountable electronic device
US5027101A (en) * 1987-01-22 1991-06-25 Morrill Jr Vaughan Sub-miniature fuse
US5040284A (en) * 1987-01-22 1991-08-20 Morrill Glasstek Method of making a sub-miniature electrical component, particularly a fuse
US5097245A (en) * 1987-01-22 1992-03-17 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5122774A (en) * 1987-01-22 1992-06-16 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5131137A (en) * 1987-01-22 1992-07-21 Morrill Glasstek, Inc. Method of making a sub-miniature electrical component particularly a fuse
US5155462A (en) * 1987-01-22 1992-10-13 Morrill Glasstek, Inc. Sub-miniature electrical component, particularly a fuse
US5224261A (en) * 1987-01-22 1993-07-06 Morrill Glasstek, Inc. Method of making a sub-miniature electrical component, particularly a fuse
US6973711B1 (en) * 2000-05-24 2005-12-13 Fonar Corporation Method for making pieces for a magnetic resonance imaging magnet
US7193494B1 (en) 2000-05-24 2007-03-20 Fonar Corporation Shim pieces for a magnetic resonance imaging magnet
TWI666819B (zh) * 2016-12-19 2019-07-21 美商雷森公司 用於製造一複合基板循環器組件及複合基板循環器組件前體之方法
US10403958B2 (en) * 2016-12-19 2019-09-03 Raytheon Company Method for making a composite substrate circulator component

Also Published As

Publication number Publication date
SE388304B (sv) 1976-09-27
AU5965673A (en) 1975-02-27
AU475049B2 (en) 1976-08-12
DE2360385A1 (de) 1974-06-12
FR2209185B1 (enrdf_load_stackoverflow) 1977-05-27
GB1443758A (en) 1976-07-28
IT996755B (it) 1975-12-10
JPS4986848A (enrdf_load_stackoverflow) 1974-08-20
FR2209185A1 (enrdf_load_stackoverflow) 1974-06-28
CA1002625A (en) 1976-12-28

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