US3446183A - Coating system - Google Patents

Coating system Download PDF

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Publication number
US3446183A
US3446183A US653390A US3446183DA US3446183A US 3446183 A US3446183 A US 3446183A US 653390 A US653390 A US 653390A US 3446183D A US3446183D A US 3446183DA US 3446183 A US3446183 A US 3446183A
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United States
Prior art keywords
coating
guns
electrodes
charging
electrostatic
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
US653390A
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English (en)
Inventor
Edward W Drum
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.)
Ransburg Corp
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Ransburg Corp
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Filing date
Publication date
Application filed by Ransburg Corp filed Critical Ransburg Corp
Application granted granted Critical
Publication of US3446183A publication Critical patent/US3446183A/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
    • B05B5/087—Arrangements of electrodes, e.g. of charging, shielding, collecting electrodes

Definitions

  • transfer efficiency of the system is less than that of an individual gun.
  • transfer efiiciency is the percentage of the coating material discharged which is deposited on the article being coated. It is believed that this reduction in eiciency is a result of a diminution of the electrostatic field gradient caused by the proximity of the charged gun bodies. The lower field gradient in the zone where the particles are charged produces a lesser charge on the coating material particles and more particles are lost.
  • lOne feature of the invention is the provision of a means establishing an electrostatic reference potential for the charging field of the devices, between adjacent devices, and at a voltage level less than that of the devices and charging electrodes.
  • conductive means are provided adjacent the discharge devices, electrically connected through resistance means to ground, establishing an electrostatic reference for the particle charging field.
  • a further feature is that reference electrodes, located between adjacent guns, are connected through resistance with ground, providing an electrostatic reference for the charging field.
  • FIGURE 1 is a diagrammatic perspective view of a coating system embodying the invention.
  • FIGURE 2 is a view of the coating device and electrode assembly looking from the right in FIGURE 1.
  • each gun has a slender charging electrode connected with a source of high voltage and establishing an electrostatic field through which the paint particles pass, becoming charged, which aids in depositing the charged particles on the grounded article to be coated.
  • the spray guns shown in the French Patent 1,421,783, which may be used in the practice of this invention, areA made substantially entirely of metal, with the charging electrode projecting forwardly from the paint discharge orifice.
  • the gun body is connected directly to the high voltage source so that the gun, in addition to the electrode, is at an elevated potential.
  • a plurality of such guns may ybe mounted in close proximity on a support as shown in French Patent 1,427,912.
  • the invention may -be utilized -with other types of discharge devices, as guns utilizing hydrostatic rather than air atomization, for example.
  • a conveyor 10 of conductive material and connected with a ground or reference potential 11, carries articles to be painted, as metal broom handles 12, through a coating zone adjacent a reciprocating mechanism 13 having a mounting arm 14 on which are carried three spray guns 15, 16 and 17.
  • the conductive bodies of the guns are mounted directly to arm 14 which is also of conductive material and is connected with a terminal of a source 18 of high voltage. The other terminal of the voltage source is connected with ground.
  • ⁇ Charging electrodes 15a', 16a and 17a project forwardly of the guns in the area where paint particles are discharged. Paint is delivered to the guns through hoses 15b, 16b and 17b. The air hoses are not shown.
  • Arm 14 is insulated Ifrom support 19 on which it reciprocates. As the articles 12 move along the conveyor, arm 14 moves upwardly along inclined support 19 and paint is discharged to coat the articles from bottom to top. Arm 14 then returns to the bottom of support 19 and the cycle is repeated. Details of the traversing mechanism are not shown.
  • the electrostatic charging fields are diffused by the proximity of a charged body, as adjacent guns or mounting arm 14.
  • the diffusion of the field reduces the coating material particle charge and transfer eliiciency of the system is less than that for a single isolated gun.
  • auxiliary electrodes 20 and 21 are provided between adjacent guns, with electrode 20 between guns 15 and 16 and electrode 21 between guns 16 and 17.
  • the electrodes are, in a preferred form of the invention, merely a conductive wire. More specifically, a length of high voltage cable has the insulating ⁇ body stripped from the center conductor for a distance of approximately one inch. The cable is supported from arm 14 between adjacent guns with the end of the center conductor aligned with the ends of the charging electrodes of the guns.
  • the intermediate electrodes 20, 21 are returned to ground 11 through multimegohm resistors 24, 25, which may be mounted at the electrodes, or may be remote therefrom.
  • a portion of the fields from each of the charging electrodes 15a, 16a and 17a terminates at electrodes 20 and 21 causing currents to flow through resist-ors 24 and 25.
  • voltages are established at electrodes 20, 21, intermediate the voltage of source 16 and the reference or ground potential.
  • the persence of the intermediate voltage between the charged guns makes the electrostatic eld more intense around the front of each gun resulting in establishment of a higher charge on the paint particles and a higher transfer efciency.
  • a further improvement in transfer eiciency can be realized by mounting additional auxiliary electrodes 26 and 27 outside guns 15 and 17.
  • the additional auxiliary electrodes the ends of which are aligned with the charging electrodes and with auxiliary electrodes 20, 21, are returned to ground through resistors 28 and 29.
  • the guns were spaced apart a distance of inches and charged from a source of the order of 120 kilovolts.
  • the auxiliary electrodes were returned to ground through megohm resistors.
  • an electrostatic system for coating grounded articles including a plurality of coating material discharge devices, principally of conductive material, for discharging particles of coating material, charging electrode means associated with said discharge devices, and a source of high voltage relative to said articles, connected with said discharge devices and charging electrode means to establish a charging field for coating particles, the devices being in such close proximity that the charging fields are diiused, the improvement which comprises: means establishing an electrostatic reference potential for said charging elds, between adjacent discharge devices, and at a voltage level lower and substantially different than that of said discharge devices and electrode means.
  • an electrostatic system for coating grounded articles including a plurality of coating material discharge devices, principally of conductive material, for discharging particles of coating material, charging electrode means associated with said discharge devices, and a source of high voltage relative to said articles, connected with said discharge devices and charging electrodes means to establish a charging field for coating particles, the devices being in such close proximity that the charging fields are diffused, the improvement which comprises: conductive means adjacent said discharge devices, electrically connected through resistance means to ground, establishing an electrostatic reference for the charging eld.
  • the coating system of claim 8 including reference electrodes located exteriorly of the end discharge devices and in alignment therewith.
  • discharge devices are located generally in side-by-side alignment with a reference electrode between each 'adjacent pair of devices and a separate resistor connected between each electrode and ground.
  • PETER FELDMAN Primary Examiner.

Landscapes

  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
US653390A 1967-07-14 1967-07-14 Coating system Expired - Lifetime US3446183A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US65339067A 1967-07-14 1967-07-14

Publications (1)

Publication Number Publication Date
US3446183A true US3446183A (en) 1969-05-27

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Application Number Title Priority Date Filing Date
US653390A Expired - Lifetime US3446183A (en) 1967-07-14 1967-07-14 Coating system

Country Status (4)

Country Link
US (1) US3446183A (enrdf_load_stackoverflow)
DE (1) DE1752730A1 (enrdf_load_stackoverflow)
FR (1) FR1571995A (enrdf_load_stackoverflow)
GB (1) GB1229282A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638612A (en) * 1969-04-24 1972-02-01 Int Standard Electric Corp Apparatus for marking conductor cables
US3848258A (en) * 1973-08-30 1974-11-12 Xerox Corp Multi-jet ink printer
US4909180A (en) * 1986-12-27 1990-03-20 Toyota Jidosha Kabushiki Kaisha Assembly of electrostatic rotary sprayers

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658009A (en) * 1948-05-13 1953-11-03 Ransburg Electro Coating Corp Electrostatic coating method and apparatus
US2754226A (en) * 1953-07-24 1956-07-10 Ransburg Electro Coating Corp Atomizing and coating system and method
US2805642A (en) * 1949-03-25 1957-09-10 Gen Motors Corp Electrostatic spray painting apparatus
US2877137A (en) * 1952-05-13 1959-03-10 Ransburg Electro Coating Corp Method of electrostatically coating an article
DE1156341B (de) * 1955-08-15 1963-10-24 Licentia Gmbh Elektrostatische Auftragsvorrichtung
DE1162728B (de) * 1958-07-28 1964-02-06 Licentia Gmbh Elektrostatische Auftragsvorrichtung
FR1427912A (fr) * 1964-03-13 1966-02-11 Devilbiss Co Appareil de revêtement de surfaces par pulvérisation électrostatique

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2658009A (en) * 1948-05-13 1953-11-03 Ransburg Electro Coating Corp Electrostatic coating method and apparatus
US2805642A (en) * 1949-03-25 1957-09-10 Gen Motors Corp Electrostatic spray painting apparatus
US2877137A (en) * 1952-05-13 1959-03-10 Ransburg Electro Coating Corp Method of electrostatically coating an article
US2754226A (en) * 1953-07-24 1956-07-10 Ransburg Electro Coating Corp Atomizing and coating system and method
DE1156341B (de) * 1955-08-15 1963-10-24 Licentia Gmbh Elektrostatische Auftragsvorrichtung
DE1162728B (de) * 1958-07-28 1964-02-06 Licentia Gmbh Elektrostatische Auftragsvorrichtung
FR1427912A (fr) * 1964-03-13 1966-02-11 Devilbiss Co Appareil de revêtement de surfaces par pulvérisation électrostatique

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638612A (en) * 1969-04-24 1972-02-01 Int Standard Electric Corp Apparatus for marking conductor cables
US3848258A (en) * 1973-08-30 1974-11-12 Xerox Corp Multi-jet ink printer
US4909180A (en) * 1986-12-27 1990-03-20 Toyota Jidosha Kabushiki Kaisha Assembly of electrostatic rotary sprayers

Also Published As

Publication number Publication date
GB1229282A (enrdf_load_stackoverflow) 1971-04-21
FR1571995A (enrdf_load_stackoverflow) 1969-06-20
DE1752730A1 (de) 1971-05-19

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