US3126300A - Device for coating the inner surfaces - Google Patents

Device for coating the inner surfaces Download PDF

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Publication number
US3126300A
US3126300A US3126300DA US3126300A US 3126300 A US3126300 A US 3126300A US 3126300D A US3126300D A US 3126300DA US 3126300 A US3126300 A US 3126300A
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United States
Prior art keywords
bulb
nozzle
channels
powder
coating
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Expired - Lifetime
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English (en)
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/12—Plant for applying liquids or other fluent materials to objects specially adapted for coating the interior of hollow bodies
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel

Definitions

  • This invention relates to devices for coating the inner surfaces of bulbs for incandescent and discharge tubes with a powder.
  • a device comprises a member for holding a bulb, a nozzle to be introduced into the neck of the bulb, which carries a first electrode and has one or more channels adapted to be connected to a powder supply, and a second electrode arranged externally of the bulb and exhibiting a potential difference relative to the first electrode, means also being provided for heating the bulb to be coated.
  • Such a device is known and is used, for example, in electrostatically coating the inner surfaces of bulbs for incandescent lamps with a thin layer of powder consisting substantially of SiO
  • an amount of finely-divided siO -powder is blown into the bulb to be treated, the wall of which has been made sufficiently conductive by heating. Due to the presence of electrodes of different potentials, arranged one on each side of the bulb surface to be coated, the finely-divided powder blown into the bulb is drawn towards the wall and expanded over the surface thereof.
  • the adhesion between the powder and the bulb wall may be improved in the usual manner, for example by means of a treatment with vapour.
  • the SiO -powder is surprisingly distributed over the bulb wall much more uniformly if channels of parts of channels in the nozzle are convergent in the indicated manner.
  • the relevant channels are preferably directed towards the axis of the neck of the bulb to be coated.
  • the nozzle is also provided with a plurality of drilled channels. It is not necessary for all of the channels in the nozzle to be convergent in the direction of spraying.
  • the center lines of at least the convergent channels in the nozzle are located on a conical peripheral surface.
  • the nozzle has a conical annular slot which is preferably adjustable.
  • This embodiment affords the advantage of a greater continuity, as reckoned over the periphery of the slot, in the supply of powder. This supply may be increased or decreased at will because of the adjustability of the slot.
  • FIGURE 1 shows an arrangement of the principal elements required for the electrostatic coating of bulbs.
  • FIGURE 2 shows the nozzle of the device of FIGURE 1, which has convergent channels in accordance with the invention.
  • FIGURE 3 is a plan view of the nozzle of FIGURE 2.
  • FIGURE 4 shows a nozzle in which the channels in the nozzle of FIGURE 2 are united into a conical slot.
  • the device shown in FIGURE 1 comprises a frame 1 in which a disc 4, provided with a V-shaped groove 3 and bearing on a plurality of balls 5, is rotatably arranged.
  • the disc 4 may be set into rotation via a rope transmission 6 by means of an electric motor (not shown).
  • a bulb holder 9 is secured to the disc 4 with the interposition of a part 8 of insulating material.
  • a circular spring 12 is arranged in horizontal tangential slots of the holder 9 so as to clamp in position a bulb, placed in the holder, at three areas.
  • a device for the supply of finelydivided powder to the wall of the bulb which device is movable in a vertical direction relative to the frame 1 and the bulb holder 9 and is to be inserted into the neck of a bulb 10.
  • the said device comprises two co-axial tubes 15 and 16.
  • the tube 15 has at its upper end a nozzle 18, which merges into a pointed part 11 and is formed as an electrode.
  • a plurality of convergent channels 19 are drilled in the nozzle 18.
  • a flow of a gas, such as air, in which an amount of SiO -powder having a particle size of preferably at most millimicrons is distributed with great fineness, may be led through the tube 15 and through the channels 19 to the interior of the bulb in the direction indicated by an arrow 17.
  • the excess powder is drawn away in the direction indicated by an arrow 20 via the space between the tubes 15 and 16 by means of a suction device, otherwise not shown.
  • a bulb 10 placed in the rotary holder 9 may be heated by the burner device 25 for the purpose of making the bulb wall to be coated of better electric conductivity.
  • the inner surface of the bulb 10 may now be electrostatically coated with a powder by providing a potential difference of, say, 15,000 volts direct voltage between the nozzle 18, formed as a negative electrode, and the burner 25, formed as a positive electrode.
  • the powder supplied in the direction indicated by the arrow 17, after having left the nozzle through the channels 19, is drawn towards the surface of the bulb and expanded over this surface.
  • a thin layer of powder once having been applied to the wall, the adhesion between the powder and the wall may be improved, if necessary, by means of a treatment with vapor.
  • a nozzle 29 screwed into the end of the inner tube 15 (FIGURE 2).
  • a nozzle 29 screwed into the end of the inner tube 15 (FIGURE 2).
  • Such a nozzle has a plurality of channels positioned in a special way. In the plan view of FIGURE 3, the channels are positioned along a circumference.
  • the channels only two of which are shown in FIGURE 2 and indicated there by 30 and 31, are drilled into the nozzle so that their main directions 35 and 36 form the surface of a cone which, in this example, has an apical angle of 30. It has been found that the introduction of a nozzle with channels convergent in the direction of spraying provides a considerable improvement in uniformity of the layer thickness of the coated bulbs.
  • FIGURE 4 comprises a nozzle having two relatively adjustable parts 37 and 38 which are the boundaries of an annular conical slot 39.
  • An annular part 41 connected by means of ridges 40 to the part 38, is screwed into the part 37.
  • Several bores 42 are provided at the upper side of the inner part 38 to permit the annular part 41 to be screwed into the outer part 37.
  • a greater continuity in the powder supply may be obtained by using a nozzle with a conical slot as shown in FIGURE 4.
  • a device for coating the inner surfaces of bulbs for incandescent lamps and discharge tubes with a powder having members for holding a bulb which is to be coated, a nozzle having at least two channels adapted to be connected to a fine powder supply in a gas above atmospheric pressure which nozzle is provided with a first electrode adapted to be introduced into the neck of a bulb, and a second electrode arranged externally along the outer surface of the bulb and exhibiting a potential difference relative to the first electrode for coating the inner surfaces of said bulbs, means also for heating the bulb to be coated, the combination comprising at least a number of the channels in the nozzle each having an outflow aperture for said fine powder, the main directions of at least those parts of the channels which lie near the outflow apertures for the powder being convergent in the direction of spraying.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
US3126300D 1960-09-02 Device for coating the inner surfaces Expired - Lifetime US3126300A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL255548 1960-09-02

Publications (1)

Publication Number Publication Date
US3126300A true US3126300A (en) 1964-03-24

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ID=19752540

Family Applications (1)

Application Number Title Priority Date Filing Date
US3126300D Expired - Lifetime US3126300A (en) 1960-09-02 Device for coating the inner surfaces

Country Status (5)

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US (1) US3126300A (en, 2012)
CH (1) CH397974A (en, 2012)
ES (1) ES270189A1 (en, 2012)
GB (1) GB951151A (en, 2012)
NL (2) NL255548A (en, 2012)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3745969A (en) * 1971-04-19 1973-07-17 Motorola Inc Offset top ejection vapor deposition apparatus
US4081709A (en) * 1975-11-20 1978-03-28 General Electric Company Electrostatic coating of silica powders on incandescent bulbs
US4112869A (en) * 1976-02-03 1978-09-12 Onoda Cement Co., Ltd. Apparatus for forming a powder layer on the surface of a metallic squeeze-out tube
US4597984A (en) * 1985-06-03 1986-07-01 General Electric Company Method and apparatus for coating fluorescent lamp tubes
EP0359560A3 (en) * 1988-09-16 1990-12-05 Glass Bulbs Limited An apparatus for manufacturing a light diffusing glass envelope
US6564772B1 (en) 2001-10-30 2003-05-20 Caterpillar Inc. Injector tip for an internal combustion engine

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2566392A (en) * 1945-06-20 1951-09-04 John A Wilkins Spray gun
US2785926A (en) * 1953-11-23 1957-03-19 Lataste Bernard Means for atomizing liquid
US2806444A (en) * 1954-12-16 1957-09-17 Westinghouse Electric Corp Silica coating apparatus for incandescent lamp bulbs
US3045925A (en) * 1959-09-29 1962-07-24 Michael N Giangualano Multiple spray apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2566392A (en) * 1945-06-20 1951-09-04 John A Wilkins Spray gun
US2785926A (en) * 1953-11-23 1957-03-19 Lataste Bernard Means for atomizing liquid
US2806444A (en) * 1954-12-16 1957-09-17 Westinghouse Electric Corp Silica coating apparatus for incandescent lamp bulbs
US3045925A (en) * 1959-09-29 1962-07-24 Michael N Giangualano Multiple spray apparatus

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3745969A (en) * 1971-04-19 1973-07-17 Motorola Inc Offset top ejection vapor deposition apparatus
US4081709A (en) * 1975-11-20 1978-03-28 General Electric Company Electrostatic coating of silica powders on incandescent bulbs
US4112869A (en) * 1976-02-03 1978-09-12 Onoda Cement Co., Ltd. Apparatus for forming a powder layer on the surface of a metallic squeeze-out tube
US4271208A (en) * 1976-02-03 1981-06-02 Onoda Cement Co., Ltd. Method for coating a metallic squeeze-out tube
US4597984A (en) * 1985-06-03 1986-07-01 General Electric Company Method and apparatus for coating fluorescent lamp tubes
EP0359560A3 (en) * 1988-09-16 1990-12-05 Glass Bulbs Limited An apparatus for manufacturing a light diffusing glass envelope
US6564772B1 (en) 2001-10-30 2003-05-20 Caterpillar Inc. Injector tip for an internal combustion engine

Also Published As

Publication number Publication date
NL255548A (en, 2012)
GB951151A (en) 1964-03-04
CH397974A (de) 1965-08-31
ES270189A1 (es) 1961-12-16
NL112394C (en, 2012)

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