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WO2000074860A1 - Procede et dispositif de revetement electrostatique atomise en poudre, et installation y relative - Google Patents

Procede et dispositif de revetement electrostatique atomise en poudre, et installation y relative Download PDF

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Publication number
WO2000074860A1
WO2000074860A1 PCT/JP2000/003684 JP0003684W WO0074860A1 WO 2000074860 A1 WO2000074860 A1 WO 2000074860A1 JP 0003684 W JP0003684 W JP 0003684W WO 0074860 A1 WO0074860 A1 WO 0074860A1
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WO
WIPO (PCT)
Prior art keywords
powder
coating
paint
flow
electrostatic coating
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.)
Ceased
Application number
PCT/JP2000/003684
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English (en)
Japanese (ja)
Inventor
Tsutomu Itoh
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Rid Corp
Original Assignee
Rid Corp
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Filing date
Publication date
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Publication of WO2000074860A1 publication Critical patent/WO2000074860A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • 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
    • B05B5/16—Arrangements for supplying liquids or other fluent material
    • B05B5/1683—Arrangements for supplying liquids or other fluent material specially adapted for particulate materials
    • 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
    • B05B7/1472—Powder extracted from a powder container in a direction substantially opposite to gravity by a suction device dipped into the powder

Definitions

  • the present invention provides a so-called electrostatic powder coating process in which a powder coating is charged, a coating powder layer is applied on a coating target, and then baked to form a coating film.
  • the ratio of the paint that is effectively applied to the substrate to form a powder layer that is, the coating efficiency, is greatly improved, and the uniformity and smoothness of the film thickness distribution of the coated film after baking are excellent.
  • the present invention relates to a thin-film coating method and an electrostatic powder coating method capable of saving paint, and a device and equipment used for the method. Background art
  • powder coatings are usually manufactured and provided in bulk, with the required particle size distribution according to the purpose of use, sealed in plastic bags and stored in one ton, or stored in a damp-proof drum. The process of transporting, handling, etc. is repeated by each of the manufacturers, dealers and users, and is finally loaded into the paint container of the powder coating machine and statically applied to the workpiece. It is electro-coated to form a powder layer. Powder coatings are fine powders with remarkably high electric resistance.In particular, recently, there has been a tendency to further finer powders for the purpose of improving the smoothness of coating films and saving paints by making them thinner.
  • the powder coating material to be put into the coating container of the powder coating machine is not an aggregate of individual particles at the time of manufacture, but rather has several to several tens of individual particles due to van der Waalska electrostatic force or the like.
  • Degree A bulk powder is formed as an aggregate containing a large amount of clusters formed by agglomeration.
  • Powder coatings in powder containers in powder coating machines (hereinafter abbreviated as “paint containers”) are usually subjected to fluidization, agitation, vibration, etc. by means of a roller.
  • the formation of clusters is further promoted by the method described above, and the powder coating material in the coating container is different from the particle size distribution at the time of manufacture, and is substantially a cluster having a substantially coarse particle size distribution. Transforms into bulk powder.
  • the powder electrostatic coating process consists of three main processes: transport of paint powder by roller. Charging of paint powder by corona discharge or tribocharging, and formation and application of paint charging cloud.
  • One of the problems that has been pointed out is that the coating efficiency and the smoothness of the coating film are inferior to those of electrostatic coating using a solvent paint.
  • few powder electrostatic coating systems took measures against coarsening of paint particles by forming clusters, and only a small annular flow path was provided at the tip of the powder electrostatic gun. Among them, there is a method in which the paint powder is swirled at high speed by air to break up the cluster.
  • this method is not versatile for the target paint, as the discharged powder spreads, and the paint is accumulated on the inner surface of the gun head due to the centrifugal force acting on the paint particles. May be troublesome, and this method is suitable when the object to be coated is a wide surface, but not suitable for an object having a complicated shape that requires a high degree of penetration.
  • the paint supply means of most conventional powder coating machines is a system in which a paint hose is connected to an injector consisting of a nozzle and a throat from a paint container, and a powder electrostatic gun is attached to the end of the hose. Is used.
  • the most effective means for crushing the cluster is the part where the compressed air blown from the nozzle passes through the throat with the Balta powder.
  • the velocity of the carrier gas in the paint hose or powder electrostatic gun is usually about 10 to 25 mZ seconds, which is almost ineffective for the crushing of the cluster. May be generated.
  • a first means for achieving the object of the present invention is to provide a powder introduction means for introducing a high-concentration paint powder into the atomization means, wherein the powder is a powder alone or a gas fluidized powder.
  • the second means is to form, by the atomization means, a high-speed thin-layer gas shear layer jet which is higher in speed than the powder flow intersecting with the powder flow, and the gas flow is usually formed by powder.
  • the gas is blown from the flat gas outlet almost perpendicularly to the powder flow from the pipe wall of the atomization means surrounding the flow, and cross-collides in the powder flow to form strong turbulence.
  • the aim is that the gas stream is present at least once over the entire cross section of the powder stream.
  • the gas flow is ejected from a flat jet outlet and made thinner, thereby reducing the proportion of the core air flow that does not contribute to the dispersion of the powder inside the gas flow, increasing the speed and increasing the tangential line along both surfaces.
  • a jet forming a shear layer where the flow velocity in the direction changes rapidly This is achieved by effectively applying a powerful shearing action to the cluster in the powder as a high-speed thin layer gas shear layer jet. Can be atomized, and the proportion used for accelerating the powder can be minimized. In addition, since all the air for atomization cross-collides in the powder stream, the powder is not accelerated in a specific direction, and the retained energy is highly efficient and is used almost exclusively for atomizing the powder. . In addition, the powder is not sprayed on the tube wall, the diffuser, or the like, so that the powder does not adhere and increase the particle size.
  • the high-speed thin layer gas shear layer jet applied to the atomization of the powder cluster is blown from the flat inlet of the pipe wall of the conduit surrounding the powder flow of the atomization means, so it is close to the inlet of the pipe wall The higher the effect. Therefore, the dispersion effect may be more effectively exhibited by guiding the powder flow to the vicinity of the pipe wall having the blowing port.
  • the gaseous two-phase flow containing paint particles which are atomized to almost single particles by the atomization means, is often diluted and conveyed by an injector consisting of a nozzle and a throat, followed by a paint hose.
  • an injector consisting of a nozzle and a throat
  • a paint hose Charged by electrostatic powder gun at hose tip
  • electrostatic powder gun At hose tip
  • electrostatically applied to the object to be coated to form an electrostatically coated powder layer The electrostatic painting process is completed.
  • the method of forming the atomized charged paint cloud is limited to the method in which the atomized charged powder paint cloud is directly sprayed by the electrostatic powder gun toward the object to be coated. Instead, a charged paint powder cladding is formed over a wide area in the booth, the object to be coated is passed through it, and the coating is performed by the charge of the charged paint particles themselves and the space charge electric field. A powder coating process using a so-called cloud chamber method can be performed.
  • the effect of the present invention is to reduce the bulk-like paint powder in the paint container, which has formed a cluster and is substantially coarsened, usually from near the entrance of the paint powder conveying path of the paint container to before the injector.
  • the atomization means By applying the atomization means, it is atomized almost to the particle size distribution at the time of manufacture, and as a result, the two-layer flow of atomized gas dust is diluted and conveyed by the injector and the paint hose, and the electrostatic powder is produced.
  • the effect is that, for example, in the case of electrostatic powder coating using a tribo electrostatic gun-clad chamber system without an external electric field, if the powder cluster is miniaturized, the powder inherently has The surface area and the number of particles are the largest, the contact area and the number of times of contact between the powder and the triboelectric charging device are the largest, and the surface area of the chargeable powder particles is also the largest.
  • the effect maximizes the specific charge of the paint powder.
  • the driving force of the charged powder particles toward the object is the product of the space charge electric field strength formed by the charged paint powder particle cloud and the charge amount of each particle.
  • the improvement in the efficiency of powder coating is improved in inverse proportion to the square of the coating powder particle size.
  • the hydrodynamic properties of the paint powder are such that the force received by the gas is proportional to the square of the particle size, whereas the weight of the paint powder is Since it decreases in inverse proportion to the third power, the particle size of the paint powder becomes smaller, and the paint powder becomes remarkably easy to get into the airflow.
  • the improvement combined with the improvement of the specific charge Q / M, significantly improved the coating property of the paint at the part of the substrate where penetration was required, and also reduced the terminal drop speed due to gravity. As a result, the sedimentation speed of the paint particles in the booth is reduced, and the same effect is obtained with the cloud chamber system in which the paint powder concentration per unit volume in the chamber is improved. As a result, it improves transfer efficiency and production capacity.
  • the effect of the gun is that the atomizable paint powder increases the chargeable surface area and the number of particles.
  • the charge efficiency is improved, and the Q / M of the charged paint powder is improved.This is due to the high voltage applied to the gun, and the synergistic effect of the electric field formed between the gun and the workpiece on the charged paint. Acceleration of powder flight increases the efficiency of coating, and also increases the density of the applied powder on the substrate.
  • the driving force of the particles toward the object is the space charge electric field due to the charged particle cloud near the object.
  • the carrier airflow blown from the gun does not normally reach the back of the object, but the lines of electric force due to the high voltage applied to the corona gun head are not affected by the carrier air, and are not affected by the carrier air. It goes around the back of Lonagan.
  • the atomized paint powder according to the present invention which has a large specific charge Q / M compared to the coarse paint powder having a small Q / M of the prior art, is coated on the lines of electric force. Ratio that goes around the back side of the coating and is applied As the paint becomes larger, the throwing power of the paint is improved, which also contributes significantly to the uniformity of the coating thickness and the improvement of the coating efficiency.
  • FIG. 1 is a system diagram of an embodiment showing the structure of a powder atomization electrostatic coating method and its apparatus according to the present invention.
  • FIG. 2 is a characteristic diagram showing characteristics of the injector nozzle and the nozzle-way valve of FIG.
  • FIG. 3 is a partial configuration diagram showing one embodiment of the configuration of the powder coating container, the atomization means, and the injector section according to the present invention.
  • FIG. 4 is a partial configuration diagram showing one embodiment of the configuration of the powder coating container, the screw feeder, the atomizing means, and the ink container according to the present invention.
  • FIG. 5 is a partial configuration diagram of one embodiment showing the configurations of the powder coating container, the table feeder, the atomizing means, and the injector according to the present invention.
  • FIG. 6 is a partial configuration diagram of an embodiment showing the configuration of the internal stirring type powder coating container, the atomizing means, and the injector according to the present invention.
  • FIG. 7 is a cross-sectional configuration diagram of a powder coating system using the electrostatic powder cladding method according to the present invention.
  • FIG. 1 shows an embodiment of the powder atomizing electrostatic coating method and the apparatus and equipment according to the present invention.
  • Fig. 1 shows an example of the basic structure of the present invention. The paint is directly sucked from a small amount of powdered paint in a carton, which has been used frequently in recent years, and applied by an electrostatic powder gun. This is a simplified illustration of the main points of an example in which the present invention is applied to a method for performing the method.
  • the powder 8 in the powder paint container 7 (usually a plastic bag input ton on a vibrating table) is repeatedly handled by manufacturers, dealers, factories, etc.
  • the bulk powder consisting of a large amount of clusters passes through the paint suction part 6 due to the suction effect generated by the nozzles 23 blown into the injectors 22 consisting of nozzles 20 throats 21.
  • Body paint 8 is introduced into pulverizing means 1 through powder introducing means 4.
  • a plurality of flat flow paths 11 which are closed toward the axis thereof are opened above the powder introducing means 4.
  • the spacer 12 regulates the thickness of the flat air passage, and the atomizer 3 having a constant flow rate determined by the normal pressure regulator 30 and the fluid resistance 3 3 passes through the flat flow passage 11 1 and the powder introduction means 4.
  • the powder inside is blown at a high speed of about 20 to 100 m / s per second, usually 50 to 80 m / s, and becomes a high-speed thin layer gas shear layer jet 10, and its strong shearing action Then, the clusters contained in the powder stream 4 are atomized into individual particles.
  • the atomizer 3 used in the atomization is mixed between the atomized powders generated as a result of the atomization to maintain individual separation.
  • An appropriate speed is about 20 m / sec, which makes the paint powder finer than in the case where the powder is fed into the throat 21 of the injector 22 as it is with the balta.
  • the volume is usually increased by about 30 times compared to the case where the bulk powder as in the conventional technology is directly fed into the injector, and the volume is increased by about 30 times compared with the case where the bulk powder is used as it is in the prior art. Since the particles are sent to the unit 21 in a distributed manner according to the axial object, the reduction in the suction performance due to the atomization unit 3 of the ejector 22 poses almost no problem.
  • the bulk paint powder in the container is sent to the injector as it is or in a fluidized state by a partial fluidizing means provided near the lower end of the paint suction part. It is usual to enter.
  • the paint powder sucked into the injector port is deflected to the throat, for example, downwardly, so that the bulk powder is ejected from the nozzle in the port by the nozzle.
  • the atomization effect can be expected only about 35 to 70%.
  • conventional electrostatic powder coating does not take into account the adverse effect of the substantial coarsening of the coating powder due to cluster formation in the coating powder coating container on the powder electrostatic coating process.
  • the paint powder is dispersed by the high-speed air flow in the injector This is thought to be due to this assumption. However, the fact that this assumption cannot be used as a prerequisite for improving the performance of the electrostatic powder coating process actually started the present invention.
  • the atomizer 3 is usually set to a constant value by the flow rate setting means 30 and 33, and the high-speed thin layer gas shear layer jet 10 is evenly distributed by the fluid resistance of the flat channel 11 and The blowing speed of the injection port 2 is always maintained at a predetermined value uniformly.
  • the high-speed thin-layer gas shear layer jet 10 exists over the entire cross section of the powder flow 4, so that the atomization action is It is always carried out over the details, and only the gas streams collide in the powder stream 4, and finally the powder is sprayed against solids such as pipes and diffusers, or by centrifugal force due to swirling flow. There is no pressing against the inner wall of the pipeline. Therefore, there are no problems such as collision welding of low-melting powder, destruction of low-strength powder, abrasion of equipment, and formation of an adhesion layer.
  • the thickness of the flat flow channel 11 is generally about 0.1 to 1 mm, and the atomizer is extremely thin, so that the core gas does not effectively affect the dispersion of the powder inside the atomizer. Since the flow rate is small and the shearing is effectively performed on both sides of the gas flow, a large atomizing shear force is obtained for the cluster. Therefore, the air blowing speed at each jet port 2 does not need to be as high as about 25 to 10 Om / sec in many cases, and the required air amount is small. For example, the weight of powder relative to gas The mixing ratio ⁇ can be as low as about 20 to 10. Also, since the mechanical structure is simple and there are no wear parts, the equipment can be made of non-adhesive materials such as teflon and high-density polyethylene. Rather, it is a simple and compact device.
  • the adjustment of the supply of the paint powder is performed by adjusting the nozzle well 23 by the nozzle well valve 27, and the conveying speed in the paint hose 35
  • the adjustment can be performed by blowing the sub-chamber 24 into the injector outlet.
  • the injector system according to the prior art is applied as it is. be able to.
  • measurement and control of the amount of air transported by the paint is also very important for performing advanced powder coating, which excels in high coating efficiency, uniformity of coating thickness distribution, and smoothness of the coating.
  • the characteristic diagram of the injector drive system of FIG. 2 and the injector nozzle and the nozzle valve of FIG. 2 show the implementation of this.
  • FIG. 2 shows nozzles 20 and nozzles when transporter 29 is held at a predetermined pressure by constant pressure valve 28 so that the pressure indicated by transport pressure gauge 32 in FIG. 1 becomes the required pressure.
  • valves 26 It does not change when any of the valves 26 is operated, and can be freely set by operating the constant pressure valve 28 by the instruction of the transfer pressure gauge 32. In this case, for 28, a normal valve is applied, to which the regulated pressure by the upstream common pressure regulating means may be supplied.
  • the nozzle supply valve 27 and the sub-ware valve 26 are operated to adjust the ratio of the nozzle-to-sub-ware, so that the paint supply amount can be set and changed over a wide range with a constant amount of transport air. Because it is easy, in a system that includes a paint powder flow meter, the output is compared with a set value and the difference is amplified.
  • the valve can be controlled by feedback control to automatically control the amount of paint supply.In this case, the amount of air to be conveyed can be obtained at a predetermined value by the constant pressure valve 28 independently of the amount of paint supply.
  • the air volume can be determined by the transfer pressure gauge 32, which is another new invention that has a wide range of applications other than the powder atomization coating system of the present invention.
  • the paint powder which has been atomized by the atomizing means 1 to almost a single particle at the time of manufacturing is supplied to the injector 22 by the nozzle 23 and the sub-layer 24.
  • the two-phase stream 19 is dispersed and uniformly diluted, and is conveyed through the paint hose 35 and charged and discharged by the powder gun 36.
  • the time required for the transfer hose to pass through the paint hose and the discharge of the electrostatic powder gun is about 1 second or less.
  • the coating powder is atomized, dispersed and suspended by the transporter to a low concentration, and has almost the same speed as the transporter. Therefore, the flocculation and recombination of the paint powder that occurs during the transfer time of 1 second or less required to pass through the paint hose 35 and the electrostatic powder gun 36 can be ignored in practical use. it can.
  • the coarse clusters which make up a significant part of the paint powder conveyed by the injector through the paint hose, are caused by gravity and bending of the paint hose.
  • the electrostatic powder gun 36 may be any of a conventionally known corona type, tribo type, or any type of electrostatic dispersing and discharging means having a combination of these.
  • An electric powder gun can be applied, and a charged atomized paint powder cloud 47 is discharged and formed into a powder coating booth 53 toward an object 40 to be coated.
  • the object to be coated 40 passes through the charged atomized paint powder cloud 47 formed in the booth 53 by the conveyor 41 to form a charged coated powder layer on the surface thereof.
  • a reciprocator, robot, etc. for changing the position and direction of the electrostatic powder gun exemplified in 39 are applied.
  • the electrostatic powder gun 36 is supplied with a powder gun 37 as needed, which may be, for example, a known corona discharge electrode protection roller or a triboelectric charging auxiliary roller.
  • Reference numeral 38 denotes a power supply for a corona-type electrostatic powder gun or an ammeter for a tribo-type electrostatic powder gun.
  • a new means for atomizing the bulk paint powder 8 is provided at a high powder concentration portion at the paint suction inlet in the paint powder container 7. 1, a new injector system 22 that makes it easy to adjust and set the amount of air to be conveyed in the paint hose 35, and its related equipment 25, 26, 27, 54, 28, 32, etc.
  • a small amount of the atomizer 3 can be used to convert the powder having substantially the same particle size distribution as that at the time when the powder was produced, which is substantially atomized compared to the prior art, into powder. It has become possible to stably eject the ink in a well dispersed state from the electrostatic gun.
  • electrostatic powder guns such as a corona-type tribo-type and a composite type thereof are used as electrostatic powder guns by the mechanism and operation described in detail in the section of the disclosure of the invention. It has a remarkable effect on improving coating efficiency, which has not been significantly improved in the course of powder coating technology development.
  • the coating object 'booth' Comparator 'reciprocator ⁇ electrostatic powder gun model ⁇ operating conditions-paint supply amount ⁇ gun applied voltage ⁇ paint hose ⁇ paint transport air volume ⁇ paint discharge pattern is the same
  • the weight of the powder applied to the object to be coated can be reduced by 10 to 10 in a practical line as compared with the case of the conventional technique without applying the atomizing means 1.
  • the increase in the weight of the applied powder varies depending on the object to be coated.
  • the lower the efficiency of application of the prior art the more the effect of increasing the weight of the applied powder is obtained, and the uniformity of the coating film thickness and It also improves sticking and coating smoothness.
  • a coating amount equal to or greater than that of the prior art can be obtained, and the uniformity of the coating thickness, the throwing power, the smoothness of the coating, and the like are improved as compared with the case of the conventional technology.
  • FIG. It is not limited only to the case where the body is introduced by the short powder introduction means 4 and pulverized.
  • FIGS. 3, 4, 5, 6, and 7 describe another embodiment of the application method of the pulverizing means 1 of the present invention.
  • FIG. 3 shows that the fluidized powder 16 fluidized by the fluidizer 13 through the pressurized chamber 14 through the perforated plate 15 in the powder paint container 7 is converted into powder by the long powder introduction means 4.
  • the powder is sucked up and down by the transporter 29 by the action of the injectors 22 above and outside the body paint container 7 and introduced into the atomization means 1, and is atomized by the atomizer 3 in the same manner as in FIG.
  • This shows another embodiment of the present invention in which a two-phase flow of atomized gaseous powder 19 is conveyed through a paint hose 35 to an electrostatic powder gun not shown in the figure.
  • the present invention can be carried out in the same manner as in FIG. 1 by the mechanism and operation described in detail in the section of the disclosure of the invention.
  • Fig. 4 shows the fluidized paint powder 16 fluidized by the fluidizer 13 through the pressurized chamber 14 through the perforated plate in the powder paint container 7 and the fluidized paint powder 16 driven by the motor 18
  • the powder 17 is drawn out from the powder paint container 7 by the screw 17, which is atomized by the atomizing means 3 by the atomizing means 3, and the paint hose 35 by the injector 22. Accordingly, the two-phase flow 19 of atomized gaseous powder is not shown in the figure, and is conveyed to the electrostatic powder gun, so that the present invention can be carried out in the same manner as in FIG.
  • the atomizing means 1 applied in FIG. 4 may pass the powder in the same structure as in FIG.
  • the atomization means 1 may be applied so that the powder passes from bottom to top.
  • the motor 18 is sometimes used for the purpose of setting and controlling the supply amount of the paint powder assuming the bulk specific gravity by setting and controlling the rotation speed.
  • Fig. 5 shows the fluidized paint powder 16 fluidized in the same manner as in Fig. 4 and the fluidized paint powder 16 drawn out by the table feeder 34 driven by the motor 18 and atomized.
  • This is an example of the case where the present invention is carried out by atomizing paint powder by means 1 and conveying the atomized paint powder to an electrostatic powder gun by an injector 22 by an injector 22, and FIG. 1, FIG. 3, FIG. 4, In Fig. 5, the same function has the same number. Is attached. Further, in the embodiments shown in FIGS. 4 and 5, it is also possible to directly extract the bulk powder in the paint container without fluidizing the paint powder, and these are also included in the scope of the present invention.
  • FIG. 6 shows another embodiment of the present invention, in which a bulk powder coating material 8 is rotated by a stirring motor 45 in an inverted conical paint container while the stirring device 46 is rotated by a stirring motor 45.
  • the coating powder is atomized by an atomizer 3 by an atomizer 1 and transported to an electrostatic powder gun by an injector 22.
  • the injector 22 is shown by a cross-sectional view perpendicular to the axis of the injector 22.
  • a perforated plate 15 at the bottom of the paint container 7 or a canvas is used in place of the perforated plate 15 to directly apply vibrating means, Stirring blades are provided in the bulk powder close to these upper parts, or a mesh member provided with vibration means is provided in the bulk powder close to the perforated plate to improve fluidization. And other measures may be applied.
  • these methods are effective in improving fluidization, they are almost ineffective in eliminating cluster formation of bulk powder in a paint container, and in many cases, powder paint is charged by agitation or the like. Promotes the formation of clusters. Therefore, this kind of powder coating container is also included in the application of the present invention.
  • the powder electrostatic gun applied to the embodiment of the present invention is composed of a powdered paint powder discharged from the powder electrostatic gun.
  • the method of forming the powder toward the object to be coated is not limited to the nozzle type electrostatic powder gun, but the dispersion and charging of the coating powder by a rotating cup or a rotating disk. It applies to all types of electrostatic powder guns, and paint powder that has been pre-charged by a tribocharger or other type of charging device inside the gun is rotated by a rotational force Any powder electrostatic coating apparatus that forms a paint powder charged cloud surrounding a workpiece by being dispersed by a disk is also included in the scope of the present invention.
  • the present invention is not limited to the electrostatic powder coating method in which the charged paint powder particle cloud is sprayed by the powder gun 36 as shown in FIGS.
  • the powder particle cloud is formed and held in a space called a booth or tunnel, and if necessary, a charging device for the cloud is installed, through which the object to be coated passes.
  • FIG. 7 shows an embodiment in which the present invention is applied to a system, which should be collectively referred to as electrostatic powder cladding, in which powder electrostatic coating is performed by applying the present invention, thereby improving performance.
  • the same functions as those in FIGS. 1 to 6 are denoted by the same reference numerals.
  • the powder dispersing and supplying means 48 uses an injector to disintegrate the fluidized powder 16 at the bottom of the booth into fine particles.
  • the charged paint powder cloud 47 is formed by the adjustment air flow 51 and the exhaust means 52 and the charging means 50 by suction through the oxidizing means 1 and the object to be coated. Coating is performed by passing 40 through a compressor 4.
  • the charged paint powder cloud 47 existing in the coating space is atomized by the atomization means 1. Because of the high charge, the sedimentation velocity due to gravity is slow, the upward velocity component of the airflow can be reduced, and the horizontal velocity component of the airflow can be reduced in a tunnel type booth. By increasing the residence time in the effective area of the booth, the value of the powder concentration in the same volume can be increased, thereby obtaining a device having a large production capacity. Other gains for this scheme according to the present invention are similar to those described with reference to FIGS.
  • the method of applying the electrostatic powder cloud illustrated in FIG. 7 is not limited to the embodiment of FIG.
  • FIGS. 1 to 7 there are various methods shown in FIGS. 1 to 7 for introducing the paint powder in the powder paint container into the atomization means. It is not limited to these as long as it can be generically referred to as body supply means and can achieve the intended purpose.
  • FIG. 6 a conventional paint supply system according to the prior art except for the atomization means 1 and the atomizer 3 according to the present invention is applied instead of the paint supply system according to the present invention shown in 1 to 9 in FIG.
  • the substrate to be coated has a force of 40 mm; a rib depth of 30 mm, a width of 45 mm and a length of 800 mm.
  • Two Lonagans were driven by a vertical reciprocating machine, and powder paint with an average particle size of 35 ⁇ m was manufactured at the time of production.
  • the production line was operated by applying a 180 ° rotation in the middle of the above, the weight of the coating powder applied to the object was 18 g.
  • the coating powder to which the atomization means 1 is applied is preferably in a bulk state or in a high concentration state such as in a fluidized state.
  • the atomization means 1 may be installed in the downstream of the injector or inside the gun. In such a case, the paint powder approaches the jet port 2 and becomes highly concentrated due to the action of a diffuser or swirling airflow, and atomization is effectively performed. Measures may be taken, and these are also included in the scope of the present invention.
  • the flat flow path 11 of the atomizing means 1 is angled toward the downstream side with respect to the powder flow, so that the atomizing means 1 is formed.
  • a weak powder conveying function can be provided, and such a case is also included in the scope of the present invention.
  • the case where air is applied to the atomization means 1, the injectors 22 and the like has been described, but other gases such as an inert gas may be applied as necessary.
  • the flat flow path 11 of the atomizing means 1 according to the present invention normally has both ends of adjacent flat flow path openings opening to the powder flow 4 in contact with each other, as shown in FIG. Suitable for long-term continuous operation of large capacity.
  • this is not always the case when the supply amount of the powder flow 4 is small, and radial pores symmetrical with respect to the central axis of the powder flow 4 can be applied.
  • powder charging means such as corona discharge or tribo charge is built in.
  • the cloud forming means is used.
  • the powder charging means may be separated from the powder charging means.
  • the powder dispersion supplying means 48 for forming the powder cloud and the charging means 50 are separately provided. The case where there is is illustrated.
  • the powder dispersion supply means 48 may also incorporate a powder charging means, which is also included in the present invention.
  • the present invention is applied to the electrostatic powder coating process and brings about an epoch-making performance improvement
  • the elements constituting the present invention are applied.
  • the dried powder is atomized with a small amount of gas and applied as a charged cloud, it can be applied to, for example, spraying of chemicals, and these are also included in the present invention.
  • the coating powder is made into single particles which are substantially maximally atomized by a small amount of atomizer, so that the corona charging or the triboelectric charging in the powder gun and the electrostatic powder are performed. Achieves the highest specific charge Q / M of charged paint powder during cladding, making it easier for paint powder cladding to ride the airflow created by electrostatic powder coating equipment and reducing sedimentation due to gravity.
  • the space charge electric field created by the charged powder cloud is maximized to improve the penetration coating property, and the wraparound electric field lines due to the gun application voltage existing on the back side of the substrate with low airflow
  • the coating powder formed by coating the powdered particles on the substrate by improving the throwing power of the coating powder by applying the powder particles to the coating, and by further reducing the particle size and the specific charge Q / M of the coating powder Flattening of body layer To achieve so-called blow-off powder coating without the need to collect and reuse paint, and to solve all the problems of long-term powder coating. I decided.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Electrostatic Spraying Apparatus (AREA)

Abstract

L'invention concerne un dispositif et un procédé de revêtement en poudre permettant d'améliorer sensiblement le rendement en pourcentage en poids d'une couche de poudre de revêtement, dispersée et formée sur un objet, sur la base d'une poudre de revêtement appliquée sur l'objet. L'uniformité de l'épaisseur du revêtement formé par chauffage et cuisson de la couche de poudre de revêtement est améliorée. Le procédé offre en outre la possibilité d'améliorer l'aptitude à la pénétration correspondant à une propriété de formation de revêtement dans des cavités dans l'objet revêtu, l'aptitude à l'étalement correspondant à une propriété de formation de revêtement sur la face arrière de l'objet revêtu, ainsi que le poli de la surface de revêtement, ce qui permet d'obtenir des revêtement en films minces et de réaliser ainsi des économies de matériaux de revêtement. Le revêtement en poudre s'effectue en flux de poudre continu à haute concentration, avec utilisation d'un flux de poudre atomisée en deux phases, d'un revêtement de poudre formé par un flux de jet gazeux en couche mince, à couche de cisaillement, plus rapide que le flux en poudre ; une collision transversale dans le flux de revêtement de poudre est réalisée de manière à former un voile de poudre de revêtement atomisé, l'objet à revêtir étant maintenu dans le voile.
PCT/JP2000/003684 1999-06-09 2000-06-07 Procede et dispositif de revetement electrostatique atomise en poudre, et installation y relative Ceased WO2000074860A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP11199407A JP2000350959A (ja) 1999-06-09 1999-06-09 粉体微粒化静電塗装方法とその装置、設備
JP11/199407 1999-06-09

Publications (1)

Publication Number Publication Date
WO2000074860A1 true WO2000074860A1 (fr) 2000-12-14

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WO (1) WO2000074860A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008012138A1 (fr) * 2006-07-25 2008-01-31 Robert Bosch Gmbh Dispositif de dosage de poudre dans un flux d'air

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5557437B2 (ja) * 2008-10-01 2014-07-23 旭サナック株式会社 粉体供給装置及び粉体塗装装置
CN102744185A (zh) * 2011-04-18 2012-10-24 浙江中博光电科技有限公司 金属粉末喷涂方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0102061A2 (fr) * 1982-08-30 1984-03-07 Ball Corporation Méthode et dispositif pour appliquer une poudre finement divisée sur une bande métallique en feuille
US5487624A (en) * 1993-02-22 1996-01-30 I.T.M. Corporation Powder feeding apparatus, electrostatic powder coating apparatus and powder flow-rate measuring apparatus
JPH08175665A (ja) * 1994-12-22 1996-07-09 Kurimoto Ltd 粉体塗料の搬送装置
JPH0924312A (ja) * 1995-07-11 1997-01-28 Ransburg Ind Kk 粉体塗装装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0102061A2 (fr) * 1982-08-30 1984-03-07 Ball Corporation Méthode et dispositif pour appliquer une poudre finement divisée sur une bande métallique en feuille
US5487624A (en) * 1993-02-22 1996-01-30 I.T.M. Corporation Powder feeding apparatus, electrostatic powder coating apparatus and powder flow-rate measuring apparatus
JPH08175665A (ja) * 1994-12-22 1996-07-09 Kurimoto Ltd 粉体塗料の搬送装置
JPH0924312A (ja) * 1995-07-11 1997-01-28 Ransburg Ind Kk 粉体塗装装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008012138A1 (fr) * 2006-07-25 2008-01-31 Robert Bosch Gmbh Dispositif de dosage de poudre dans un flux d'air

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