Classifications

• • 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
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
  • B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements
  • B05B3/10—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces
  • B05B3/1035—Driving means; Parts thereof, e.g. turbine, shaft, bearings
  • B05B3/1042—Means for connecting, e.g. reversibly, the rotating spray member to its driving shaft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
  • B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements
  • B05B3/10—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces
  • B05B3/1064—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements discharging over substantially the whole periphery of the rotating member, i.e. the spraying being effected by centrifugal forces the liquid or other fluent material to be sprayed being axially supplied to the rotating member through a hollow rotating shaft
• • 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
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/04—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces
  • B05B5/0403—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces characterised by the rotating member
  • B05B5/0407—Discharge apparatus, e.g. electrostatic spray guns characterised by having rotary outlet or deflecting elements, i.e. spraying being also effected by centrifugal forces characterised by the rotating member with a spraying edge, e.g. like a cup or a bell
• • 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
  • B05B5/025—Discharge apparatus, e.g. electrostatic spray guns
  • B05B5/053—Arrangements for supplying power, e.g. charging power
  • B05B5/0533—Electrodes specially adapted therefor; Arrangements of electrodes

Definitions

• the invention relates to a spray bowl and to an electrostatic rotary sprayer for coating product equipped with such a bowl.
• the bowls made of an insulating material do not allow the coating product to be electrostatically charged, so that additional means for charging the coating product must be provided by Corona discharges or emanations.
• the charge of the coating product obtained is less effective, so that the effect of the electrostatic field on the coating particles is less, the deposition efficiency obtained being relatively low.
• Bowls made of a conductive material make it possible to electrostatically charge the coating product when it flows in contact with the surfaces of the bowl which is brought to high voltage by any suitable means. These bowls generally have the drawback of constituting significant electrical capacities, potentially dangerous for a user and capable of creating electrical arcs capable of starting a fire in the explosive atmosphere of a coating booth.
• electrostatic coating materials and their peripherals are subjected to extensive safety tests to ensure that they are not likely to cause an electric shock, the energy of which would be greater than a predetermined threshold value.
• Some standards provide for example that the breakdown or discharge energy, between a part of the sprayer brought to high voltage and a sphere of small radius placed at a distance of the order of a centimeter, must be less than 0.24 mJ . Such a value cannot be observed with a known bowl made of electrically conductive material because the edges and the flat surfaces which it comprises, in particular in the vicinity of the discharge edge of the coating product, are liable to give rise to discharges of much higher energy.
• the invention more particularly intends to remedy, by proposing a spray bowl allowing charging by contact of the coating product and for which the discharge or "breakdown" energy is maintained at a level lower than that imposed by the most restrictive standards.
• the invention relates to a spray bowl for an electrostatic rotary projector for coating product, said bowl comprising a flange for distributing the product intended to be brought to high voltage during operation of the projector, so as to electrostatically charge the contact product, characterized in that the flange is electrically connected to at least one corona discharge device from a tapered tip end, this tapered tip end being arranged in the vicinity of a outer surface of the bowl.
• the flange which constitutes the central part of the bowl, allows charging by contact with the coating product during flow.
• the discharge element (s) create privileged paths of fragrance between the flange and the outside of the bowl, so that no energy accumulation is possible at a level such that the breakdown energy would exceed the admissible values .
• the approximation of the object leads to an increase in the effluvium current resulting in a drift of the current consumed, this drift being able to be detected by a high voltage generator used to supply the bowl flange with high voltage.
• known generators such as in particular from patent application EP-A-0 219 409 in the name of the Applicant, are capable of reacting to an abnormal variation of the current.
• the variations of current generated by the discharge element (s) when an object to ground is approached are detected early enough by the generator for the latter's safety function to cut off the power supply before 'a potentially dangerous energy discharge is not possible.
• the bowl comprises several discharge elements regularly distributed around its axis of rotation.
• This multiplicity of discharge elements makes it possible to obtain, when the bowl is energized, the desired effect with a symmetry of revolution around the axis of rotation of the bowl, including in the absence of rotation.
• this distribution avoids a dynamic imbalance of the bowl, that is to say an unbalance not admissible at the rotation speeds considered.
• the flange is bordered, at its outer periphery, by a generally annular piece made of a material electrically more insulating than the material of the flange and forming an edge or spraying edge of the bowl and the current discharge element is formed by an insert made of a material electrically more conductive than the annular part and disposed in this annular part, in electrical contact with the flange, this insert extending as far as the vicinity of a external surface of the annular part.
• the annular part located at the periphery of the flange avoids the risk of electrical breakdown between the flat surfaces brought to high voltage and a neighboring object brought to ground.
• the inserts which are advantageously but not necessarily metallic, constitute particularly effective discharge elements through the insulating or semiconductive layer produced by the annular part around the flange.
• the insert is partially received in a hole made in the flange driver.
• This particularly simple construction ensures effective electrical contact between the flange and the insert, while guaranteeing its positioning relative to the other constituents of the bowl.
• the deflector carries at least one discharge element extending to an external surface, known as the front face, of the deflector.
• the discharge element is an insert arranged along the axis of rotation of the bowl.
• the insert (s) is or are in the form of a needle and provided with at least one tip-shaped end, this end being flush with the external surface of the annular part or of the deflector.
• at least one insert carries a collar capable of cooperating with an internal shoulder of a housing for receiving the insert.
• At least one insert is provided with two tip-shaped ends, these ends being flush with two external surfaces of the annular part, these external surfaces being oriented respectively towards the axis of rotation. and out of the bowl.
• the end of the insert close to the external surface of the bowl is arranged near the spraying edge.
• This arrangement is particularly advantageous, since it is near the spraying edge that there is the greatest risk of an obstacle to ground, such as a hatch or an unclosed door on a motor vehicle body. being coated.
• the discharge element is formed by a point shaped on the external surface of the flange.
• This aspect of the invention makes it possible to produce a fully conductive bowl, which is particularly effective for charging by contact with the coating product, while avoiding the aforementioned problems of discharge with potentially dangerous energy levels.
• the points formed by the discharge elements are supplied with high voltage by the mass of the flange and constitute as many privileged discharge points by corona.
• the point or points are formed in a single piece with the flange.
• the invention also relates to an electrostatic coating product projector which comprises a bowl as described above and means for electrically connecting the flange of this bowl to a high voltage generator, this generator being able to detect variations in the current. corona passing through the bowl discharge element (s).
• This projector meets the most demanding standards in terms of security, which corresponds to very high operational reliability.
• FIG. 1 is a schematic representation of principle of an electrostatic rotary projector of a coating product according to one invention
• FIG. 2 is a front view on a larger scale of the bowl used with the projector of Figure 1;
• FIG. 3 is a section along line III-III in Figure 2;
• FIG. 4 is an enlarged view of two details IV of Figure 3;
• Figure 5 is a view similar to the part upper of Figure 4 for a bowl according to a second embodiment of the invention.
• Figure 6 is a section similar to Figure 3 for a bowl according to a third embodiment of the invention.
• an electrostatic rotary projector 1 of coating product comprises a rotor 2 driven in rotation by any suitable means and, in particular by an air turbine or an electric motor.
• the rotor 2 carries an elastic ring 3 which can be in accordance with the technical teaching of EP-A-0 697 917.
• the elastic ring 3 makes it possible to make a spray bowl 4 integral with the rotor 2.
• the rotor 2 is crossed by a fixed duct 5 for supplying coating product to the vicinity of a central orifice 6 for feeding the bowl 4 formed in a flange 7 extending generally perpendicular to the axis of rotation XX 'of the rotor 2, ring 3 and bowl 4.
• the rotor 2 is made of an electrically conductive material, for example metallic, and connected by any suitable means to a high voltage generator 8.
• the ring 3 and the flange 7 are also made of electrically conductive materials, so that the high voltage from generator 8 is transmitted to the flange 7.
• the flange 7 is therefore able to electrostatically charge, by contact, the coating product which flows on its surface when it is supplied with high voltage by the generator 8 during operation of the projector 1.
• the bowl 4 also comprises a deflector 9 disposed opposite the outlet orifice of the conduit 5 relative to the flange 7, that is to say facing a surface 7a., Called the front face, of the flange 7.
• the deflector 9 is pierced with four conduits 10 allowing, during the bowl cleaning phases, the flow of part of a solvent coming from the conduit 5 on its surface 9a. directed towards the outside and called the front face.
• the deflector 9 is immobilized with respect to the flange 7 by screws 11 passing through the flange 7 and penetrating into the rear bosses 9b of the deflector 9.
• the part 20 is advantageously glued to the flange 7. It is also noted that the respective shapes of the parts 7 and 20 contribute to immobilizing the part 20 on the flange 7 by cooperation of shapes.
• Needle-shaped metal inserts 22 are housed in eight blind holes 23 formed both in the part 20 and in the flange 7.
• Each insert 22 comprises a first end 22a_, in the shape of a point, disposed flush with the external surface 20a, of the part 20 near the spraying edge 21.
• the second end 22b is pressed into the bottom of the bore 23 which is formed in the part 7b of the flange 7.
• the inserts 22, which are metallic, are permanently brought to the same electrical potential as the flange 7.
• a discharge line L is created as shown in dotted lines.
• the inserts 22 therefore constitute as many discharge elements by emanation from the bowl 4.
• the discharge line L results in a current consumption which can be detected by the generator 8 according to known techniques, in particular from EP-A-0 219 409 The generator is then able to react to this sudden increase in current by cutting off the supply to the bowl in order to prevent the energy level potentially reached during a spark discharge from being greater than an imposed value. It is understood that the fact that the bowl comprises several inserts 22 distributed around the axis XX 'makes it possible to multiply the effect described above and to ensure its symmetry around this axis.
• a second series of eight inserts 25 is arranged through the part 20 and the external radial part 7b of the flange 7, each insert 25 comprising a first end 25_a in the form of point arranged in the immediate vicinity of the outer part 20 ⁇ of the outer surface 20a .
• the tips 25a. inserts 25 are directed towards the rear of the bowl 4, in the direction of the external surface of a cover 12 of the headlight 1 shown in phantom in Figure 1. In fact, no grounded object can be approached from the tips 25a. through the cover 12 which is insulating, so that this cover limits the area of potential approach of an object to ground.
• Each insert 25 carries, at its second end 25b, a head or flange 25ç_ capable of cooperating with a shoulder 26a. of a receiving hole 26 of the insert 25. This makes it possible to position the first end 25a of the insert 25 with precision with respect to the external surface 20 ⁇ of the part 20.
• a plug of glue or resin 27 is advantageously disposed in the part of the bore 26 opposite the point 25a, so that the part 20 ⁇ of the external surface 20a, directed towards the axis XX 'does not have any irregularities in which could accumulate the coating product.
• an insert 28 is disposed in the deflector 9 and comprises a first end 28a, in the form of a point, arranged flush with the front face 9a , of the deflector 9. If the deflector 9 is made of electrically conductive material, the insert 28 is brought to the same electrostatic potential as the flange 7, so that it is capable of generating a discharge line, as explained above with reference to the inserts 22 and 25 It should be noted here that, even if it is disposed within an electrically conductive surface brought to high voltage through the bosses 9b, the tip of the insert 28 constitutes a privileged zone of discharge with respect to the surface 9a_ of the deflector 9.
• the emanations generated at the tips of the inserts 25 and 28 are detected by the generator 8.
• the deflector 9 is made of electrically insulating material, in which case the insert 28 is brought to a floating potential.
• the tip 28a also serves for the effluvium of the electrostatic charges drained by the insert 28 at the surface of the deflector 9.
• the insert 28 prevents the electrical capacity of the duct 5, of its support and of the turbine associated with the rotor 2 is not discharged through the ducts 10 for rinsing the front face 9a . of the deflector.
• the inserts 25 include a tapered tip at each end 25a, or 25b. This also makes it possible to create a discharge line L "on the side of the surface 20a ⁇ of the part 20 when a sphere S, at earth potential, is approached in the direction of the point 25b.
• the point ends 25b avoid the creation of electric arcs or discharges of high energy between the front circular edge 9ç_ of the deflector and an object grounded in the position of the sphere S in FIG. 5.
• the presence of the flange 25.ç_ and of the shoulder 26a guarantees that the inserts 25 are not likely to be ejected from the bowl under the effect of the intense centrifugal forces which they undergo from makes high rotation speeds of the spray bowl which can reach, or even exceed, 80,000 revolutions per minute.
• the material used for the manufacture of the flange 7 is advantageously based on aluminum, which allows it to have good dimensional stability, this property being essential during the rotation of the bowl at high speed.
• the material used for part 20 can be a polyoxymethylene resin.
• the inserts 22, 25 and 28 can be made of steel or aluminum.
• the annular part 20 can also be made of a semiconductor material, since it is sufficient for the part 20 to have a resistivity greater than that of the inserts 22 or 25 for these to constitute privileged discharge paths. According to another alternative and when the part 20 is made of an electrically insulating material, it can be provided that the inserts 22 and 25, or even the insert 28, are made of a semiconductor material.
• the bowl 54 shown in Figure 6 can be mounted on the projector shown diagrammatically in FIG. 1.
• This bowl essentially comprises a flange 57 made of an electrically conductive material on which a deflector 59 is fixed by means of several screws 61.
• This bowl differs from those of the previous embodiments essentially in that it does not include an annular part that is more insulating than the flange 57, but on the contrary in that the flange 57 extends radially to the outside so as to constitute the spraying edge 71.
• 57ç_ the peripheral surface external of the flange 57.
• points 75a On this surface 57c ⁇ are provided several pins or points 75a, integrally formed with the flange 57. In the same way, several points 72 so nt provided on the spraying edge 71. Finally, points or pins 75b are arranged on an internal surface 57d of the flange 57 directed towards the deflector 59. As before, the points 72 to 75a, and 75b constitute as many privileged areas of discharge of the electrical capacity formed by the flange 57 as a whole. The variations in current consumption induced by the emanations, during the creation of a discharge line, in particular by approaching an object of ground, can be detected by the generator 8 mentioned with reference to the first embodiment.
• the points or pins 72, 75a, and 75b have a height h by relative to the spraying edge 71 or to the surfaces 57c . and 57d . on the order of 1 to 2 mm, which allows them to create discharge zones by corona without presenting a dangerous character for a user who handles the bowl 54.
• the deflector 58 can be equipped with a corona discharge insert, or even provided, in its central part, with a point of the type of points 72.

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• Electrostatic Spraying Apparatus (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9524915

Family Applications (1)

Country Status (16)

Cited By (1)

Families Citing this family (10)

Family Cites Families (15)

• 1998
  • 1998-04-01 FR FR9804269A patent/FR2776946B1/fr not_active Expired - Lifetime
• 1999
  • 1999-03-26 TW TW088104799A patent/TW429168B/zh not_active IP Right Cessation
  • 1999-03-31 CA CA002320880A patent/CA2320880A1/fr not_active Abandoned
  • 1999-03-31 US US09/647,198 patent/US6347754B1/en not_active Expired - Lifetime
  • 1999-03-31 AU AU29413/99A patent/AU2941399A/en not_active Abandoned
  • 1999-03-31 WO PCT/FR1999/000752 patent/WO1999049982A1/fr active IP Right Grant
  • 1999-03-31 CN CN99803823A patent/CN1120056C/zh not_active Expired - Fee Related
  • 1999-03-31 TR TR2000/02697T patent/TR200002697T2/xx unknown
  • 1999-03-31 HU HU0102390A patent/HUP0102390A2/hu unknown
  • 1999-03-31 DE DE69909605T patent/DE69909605T2/de not_active Expired - Lifetime
  • 1999-03-31 ES ES99910470T patent/ES2203089T3/es not_active Expired - Lifetime
  • 1999-03-31 KR KR1020007009618A patent/KR100564289B1/ko not_active IP Right Cessation
  • 1999-03-31 BR BR9908740-5A patent/BR9908740A/pt not_active Application Discontinuation
  • 1999-03-31 EP EP99910470A patent/EP1068022B1/de not_active Expired - Lifetime
  • 1999-03-31 PL PL99343080A patent/PL343080A1/xx unknown
  • 1999-03-31 JP JP2000540940A patent/JP2002509795A/ja active Pending

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