Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
  • B05B7/1404—Arrangements for supplying particulate material
  • B05B7/144—Arrangements for supplying particulate material the means for supplying particulate material comprising moving mechanical means
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S198/00—Conveyors: power-driven
  • Y10S198/952—Heating or cooling

Definitions

• the invention relates to a method of supplying a plant for spraying a powdery product, in particular a powder coating product. It also relates to an installation for projecting such a pulverulent product.
• the pulverulent product usually called “powder” is brought from a product reservoir to its point of use, for example a pneumatic or centrifugal type projector.
• the powder is entrained by means of an air jet in a long, often tortuous and relatively small diameter duct.
• a suction device of the Venturi type can be used.
• the powders used are generally intended to be cooked at around 180 ° C after being applied. However, it has been noted that this cooking phase causes certain powders to turn yellow. New powders have been developed which only require cooking at around 140 ° C. This solves the problem of yellowing but introduces an additional constraint because these powders deteriorate quickly at room temperature. They should be stored at low temperatures, preferably between 5 ° C and 10 ° C. Furthermore, the point polymerization of these powders is low and they may polymerize in places where the temperature tends to be high, such as around the worm of a mechanical drive system. It is necessary to keep in the tank only the powder consumed in a period shorter than that beyond which the powder deteriorates. This requires frequent filling of the tank.
• the powder must travel a relatively long path of the order of ten meters for example, in the conduit located between the supply device and the projector with which it is associated. Friction in this duct can raise the temperature of the powder and deteriorate or cause it to polymerize.
• the reservoir and the associated drive system necessarily contain powder residues. They must be completely emptied of the powder and it must be stored in a cool, dry place such as a refrigerator for the duration of the shutdown of the installation.
• One of the essential advantages of coating with a pulverulent product is that the product which has not reached the target, that is to say the object to be painted, can be recycled by means of an appropriate device for recovering the powder in the cabin and to a device for transporting this recovered powder to the powder supply device of the installation where it is mixed with new powder.
• the powder undergoes heating during projection, if its temperature at the outlet of the device is too high, so it may not be recoverable.
• the powder recovered may raise the temperature of the new powder during mixing, even if the latter has been stored in a refrigerator until it is poured into the reservoir of the supply system.
• the invention solves all of these problems. It relates to a method of supplying an installation for spraying a pulverulent product such as in particular a powder coating product, characterized in that said product is cooled inside the product supply device of said installation.
• the temperature of the powder is kept below 15 ° C, preferably between 5 ° C and 10 ° C. It is possible to provide reservoirs large enough to contain the powder necessary during a working day, or even more. It is no longer necessary to empty the powder from the reservoir and the body surrounding the worm, at the end of the work period. This avoids the deterioration of the powder, in particular its polymerization, in places of the feed device where heating occurs, for example by friction, such as the sheath surrounding the worm. In addition, if the powder is collected in the cabin, it is quickly brought back to the right temperature as soon as it returns to the tank.
• the temperature in a coating workshop can vary significantly, for example depending on the season.
• the mechanical and chemical properties of the powder vary according to this temperature: it will be more or less "sticky", and will agglomerate more or less depending on the temperature. Thanks to the process of the invention, the powder is used under optimal conditions throughout the year.
• the invention also relates to a device for supplying an installation for spraying a powdery product, such as for example a powder coating product, comprising a reservoir and a mechanical transport member, characterized in that it comprises means for cooling the powdery product.
• These cooling means can consist of only one or of the combination of several of the following systems: a system for fluidizing the powder in the installation reservoir from cold air,
• FIG. 1 is a schematic view of a device for transporting powdery product according to the invention.
• FIG. 1 is a view of a worm according to a variant of the invention.
• the device of FIG. 1 comprises a reservoir 1 of fluidized powder whose bottom consists of a porous plate 2 through which a gas such as air is injected to fluidize the powder and entrain it towards an opening 3.
• the latter is made in the bottom of the tank 1 and is extended by a body 6 forming a hopper in which a worm screw 4 is installed. driven by a motor 5, for example an electric motor.
• One end of the body 6 on the downstream side of the worm 4 forms a sheath 7.
• the body 6 has, in its lower part, a drain opening closed by a removable plug 8.
• a vibrator 9 is mounted on the body 6 , outside of it.
• the assembly constituted by the reservoir 1 and the body 6 is thus vibrated.
• a thermal seal 5 ′ is placed between the motor 5 and the worm 4.
• the device also comprises a drive nozzle 10 connected to the outlet of the sleeve 7 and comprising an injector 11 supplied with air by a compressed air supply duct 14 connected to a control panel 13.
• the source of compressed air and possibly the necessary regulator are not shown.
• the outlet of the nozzle 10 is connected to a flexible conduit 15 supplying powder to an electrostatic projector 16, for example automatic.
• the powder recovered in the cabin (not shown) of the installation and intended to be recycled is returned to the supply device by a conduit whose inlet 35 opens at the upper part of the reservoir 1.
• the fluidizing air from the reservoir 1 is supplied to a distribution chamber 23, located under the porous plate 2, by a supply of dry air 24, through a duct 25.
• the dew point of the air supplied for the fluidization is at 2 ° C and this air is cold, that is to say at a temperature below 15 ° C, preferably between 5 ° C and 10 ° C.
• the temperature of the powder in the reservoir 1 is thus kept at a low value independent of the outdoor temperature conditions which can vary greatly from season to season.
• a heat exchanger 30 supplies, through a conduit 31, with cold water or freon, an annular chamber 32 defined around the sheath 7. This device makes it possible to cool the sheath 7 and the powder which is located inside.
• the circuit formed by the duct 31 and the chamber 32 is not closed directly on the heat exchanger 30 but also includes a coil 33 housed in the hopper, below the opening 3, that is to say on the path of the powder falling from the reservoir 1 onto the endless screw 4.
• a return duct 34 closes the cooling circuit of the exchanger 30.
• the powder located in the body 6 is permanently maintained at a temperature low enough that its conservation is not too significantly limited in time.
• the air injected into the duct 14 is at a low temperature, for example close to that of the air used to fluidize the powder in the reservoir 1. This air can be supplied by the supply 24.
• the powder which has been cooled in the supply device is maintained at an adequate temperature until it arrives in the projector 16.
• the endless screw 104 shown in FIG. 2 has, in its axial part, two channels 105 and 106 for circulation of a cooling fluid supplied by a unit similar to the heat exchanger 30 of FIG. 1.
• the channel 105 communicates with an axial rotary joint 107 mounted at one end of the screw, while the channel 106 opens out by a radial bore in an annular chamber 108 defined in the vicinity of this same end of the screw around a cylindrical portion of the latter . Seals are provided at the interfaces of the moving parts in contact to ensure the necessary sealing of the coolant circulation circuit.
• the two channels 105 and 106 meet at the other end of the endless screw 104 in a widening closed by a plug 110. This device makes it possible to maintain the endless screw 104, and in particular its fins at a temperature low enough to avoid polymerization of the powder on the fins.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Nozzles (AREA)
• Electrostatic Spraying Apparatus (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9447355

Family Applications (1)

Country Status (8)

Families Citing this family (10)

Family Cites Families (10)

• 1993
  • 1993-05-24 FR FR9306137A patent/FR2705591B1/fr not_active Expired - Fee Related
• 1994
  • 1994-05-19 CA CA002161963A patent/CA2161963C/fr not_active Expired - Fee Related
  • 1994-05-19 ES ES94917032T patent/ES2112544T3/es not_active Expired - Lifetime
  • 1994-05-19 US US08/553,440 patent/US5836722A/en not_active Expired - Fee Related
  • 1994-05-19 BR BR9406276A patent/BR9406276A/pt not_active IP Right Cessation
  • 1994-05-19 DE DE69408318T patent/DE69408318T2/de not_active Expired - Fee Related
  • 1994-05-19 EP EP94917032A patent/EP0703832B1/de not_active Expired - Lifetime
  • 1994-05-19 WO PCT/FR1994/000592 patent/WO1994027731A1/fr not_active Ceased

Non-Patent Citations (1)

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