Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/002—Processes for applying liquids or other fluent materials the substrate being rotated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
  • B05D3/0218—Pretreatment, e.g. heating the substrate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
  • B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
  • B05D3/0254—After-treatment

Definitions

• This invention relates to the varnishing of articles that are capable of being rotated.
• the invention is applicable particularly to the varnishing of armatures, for which reason it may be described with particular reference thereto.
• a customary practice has been to dip armatures in varnish for a comparatively long period of time to permit the varnish to penetrate as completely as possible into the interstices of the armature by gravity or capillary action, and sometimes by use of vacuum impregnating tanks, and then to suspend them vertically to cause excess varnish to drain ofl. Thereafter the armature is baked to evaporate the varnish solvent and to oxidize the varnish film, and in the case of heat convertible resin varnishes to cure the resin film also.
• armatures and other rotatable parts may be varnished more rapidly, more satisfactorily and more economically than according to the above-described prior practices by heating them .to a temperature such that upon rotative contact with the varnish the solvent will be caused to evaporate promptly from the film or coating of varnish that adheres to the surface as the armature emerges from the bath.
• the armature is heated to a temperature at least approximately that of the boiling point of the solvent used in the varnish.
• the thus heated article is then rotated in a bath of varnish to apply varnish onto the part which requires it, after which it is rotated freely, i. e., without contact with the varnish bath, to distribute the varnish uniformly and allow it to penetrate, and then subjected to baking heat while rotating it.
• both the solvents and the resins used in making electrical varnishes vary widely.
• the temperature at which the armature is heated initially will depend upon the particular varnish that is used, and particularly upon the solvent which it contains. Accordingly, specific temperatures or ranges of temperature applicable to all purposes and to all varnishes can not be stated. Due regard will be given, of course, to the varnish-forming constituents to avoid premature reaction or hardening.
• This factor of the invention is illustrated, however, by the case of a varnish containing a heat-convertible phenol-formaldehyde type condensation product and petroleum naphtha as a solvent. With this varnish it suflices to heat the armature to about 275 to 300 F.
• the armature is rotated While it is being heated.
• heating is effected 3 by infra red radiation although it can be accomplished in various other ways known to the art, e. g., by currents induced in the armature and of a frequency adapted to produce the desired heating through the necessary depth.
• the heated armature is then rotated in a bath of varnish, the. bath level being so adjusted that only the portion which is to be varnished moves through it, which avoids getting Varnish on the shaft and other parts that do not require varnish.
• the solvent begins to be evaporated, or to boil oil, and under the influence of the heat of the armature the solvent is driven promptly from the coating of varnish which adheres tothe armature as it emerges from the bath.
• the net is substantially solvent-free.
• the armature is then removed from the bath (or the bath is lowered from the armature) and rotated to insure uniform distribution of the varnish coating, following which it is subjected to a baking temperature while continuing to rotate it, the heating being performed in any suitable way, for instance as referred to above.
• a very short pre-baking rotation sufllces.
• armatures for an aircraft fuel pump motor. These armatures had an overall length of 5 /2 inches. They were treated with a thermosetting phenol-formaldehyde type varnish containing petroleum naphtha as the solvent. The armatures were heated to a temperature of about 300 F. during 15 minutes, rotated once at a speed of 1 R. P. M. in the varnish, rotated slowly for 2 minutes after removal from the varnish,
• Varnish loss by drainage in the prior dipping practice has constituted a major expense item. From a total of 25 armatures treated in accordance with the presentinvention only 4 drops of varnish" drained away.
• Armatures treated as just described successfully pass the speed and heat test to which these devices are put before acceptance. Armatures treated in accordance with the prior dipping practice do not consistently pass that tes after baking for 6 hours. I
• the armatures may be rotated in a varnish bath of the least practicable volume with maintenance of its level through periodic or continuous addition of fresh varnish, or a large volume of varnish may be used with circulation for cooling it to prevent undue temperature rise.
• That method of varnishing an armature which comprises heating the armature to a temperature at least approximately that of the boiling point of the varnish solvent, rotating the heated armature slowly, through the varnish and thereby applying thereto a coating of varnish substantially free from solvent, removing the thus coated armature from said bath and rotating it slowly to cause the varnish coating in its substantial entirety to penetrate it, and then heating it to bake the varnish while continuing to rotate it.
• That method of impregnating an electrical winding with electrical varnish which comprises supporting the winding for rotation, rotating the winding and heating it at least to approximately the boiling point of the varnish solvent, rotating the heated winding in a bath of the varnish and thereby applying thereto a coating of varnish substantially free from solvent, and removing the thus coated winding and heating it to bake the varnish while rotating it slowly and retaining in substantial entirety all of the varnish coating.

Landscapes

• Application Of Or Painting With Fluid Materials (AREA)
• Manufacture Of Motors, Generators (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24054724

Family Applications (1)

Country Status (3)

Cited By (7)

Families Citing this family (1)

• 1943
  • 1943-12-30 US US516241A patent/US2411180A/en not_active Expired - Lifetime
• 1944
  • 1944-06-08 GB GB11006/44A patent/GB584445A/en not_active Expired
• 1949
  • 1949-10-20 DE DEST46A patent/DE835123C/de not_active Expired

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