MXPA97005060A - Po atomizer - Google Patents

Abstract

The present invention relates to a powder atomizer, characterized in that it comprises a tray, an articulated element for rotation about an axis, the tray partially surrounds the element and with it defines a venturi tube inside which powder is fed, the tube Venturi has an inlet inside which dust is fed, and a separate outlet, a motor that rotates the element inside the tray at an excess speed necessary to throw the powder from the centrifugal force element and extract gas through the tube venturi so that the powder is fed into the inlet and atomized, and produces a uniform cloud of particulate material, and a means to minimize the electric charge on the tray and in this way results an agglomeration of particulate material in the

Description

DUST ATOMIZER Cross Reference to the Related Request.

This is a continuation in part of the pending US Patent Application Serial No. 08 / 680,243, filed July 10, 1996.

Background of the Invention The present invention relates to devices used to distribute a measured volume of powder from a hopper to an air stream, and refers more particularly to a powder atomizer that can be combined with a deagglomerator and feeder to distribute measured quantities of atomized powder in a stream of air in the form of a moving cloud of particulate material. In the past, powders have been atomized in a different number of ways. Hoppers have been used to feed the powders to the fluid streams of air. However, the hoppers have been unsatisfactory in feeding the powder due to the formation of bridges in the powder or to the electrostatic forces that REF: 25062 are present between the material in the form of dust particles. The flow rate can also be affected by variables such as humidity, particle size, particle shape, density, material cohesiveness, chemical composition, hopper configuration and electrostatic forces between the particulate powder. Additional problems are encountered when precise quantities of powder need to be administered, at instantaneously uniform flow rates, and when the administered powder tends to agglomerate. Therefore, it is highly desirable to provide an improved powder atomizer, an improved combination of atomizer and powder feeder, and an improved combination of deagglomerator, atomizer and powder feeder. It is also highly desirable to provide an improved powder atomizer, an improved combination of atomizer and powder feeder and an improved combination of deagglomerator, atomizer and powder feeder, which can distribute accurately measured amounts of powder to air streams that they flow controllably uniform. The hoppers, even when complemented by vibrators, are not uniformly uniform in the dosage of the powder, in precisely measured quantities, in coating operations. Additional problems are encountered with the coating of wide substrates when it is intended that the powder feed through a hopper be atomized in a fluid stream of air, since the air used to atomize the powder is more or less two-dimensional, i.e., longitudinally, and in a lateral dimension. For wide mesh applications, this air stream is generally flat and relatively low velocity. As such, it does not apply the locally high speed cutting forces required to de-agglomerate the powder from the feeder, and consequently, the cloud may include agglomerated particles of greater thickness and heavy currents of non-uniform concentrations of material in the form of particles that are undesirable in many processes. Therefore, it is highly desirable to provide an improved powder atomizer and an improved combination of powder feeder and atomizer and an improved combination of deagglomerator, feeder and powder atomizer for wide mesh coating operations that can produce deagglomerated clouds of material in Particle shape, with a relatively uniform size, which is relatively uniform both transversely and longitudinally to the mesh. Recently, quantities of powder material, accurately measured, in air streams can be dosed and atomized using material feeders such as those described in U.S. Patent No. 5,314,090, and the size of the particulate material in the cloud is it can be made more uniform by using a deagglomerator as described in US Pat. No. 5,035,364. While the combination of this material feeder and deagglomerator is capable of producing uniform clouds of material in the form of particles that are uniform both in the size of the particles and in the distribution and both transversally and longitudinally to the cloud, the combination does not produce uniform clouds of particulate material in wide mesh applications such as powder coating of rolled metal sheets, and conveyors with closely grouped articles to be coated. Grouping a plurality of combinations of material feeders and deagglomerators, side by side, produces a cloud that can be uniform in particle size longitudinally of the cloud flow. However, non-uniformity is still present transversally of the cloud due to overlap and scratching. Therefore, it is highly desirable to produce an improved powder atomizer and a combination of powder feeder and atomizer and an improved combination of atomizer, deagglomerator and powder feeder that is capable of producing clouds of particulate material that are relatively uniform. both longitudinally and transversely to the cloud and containing particulate material of a relatively uniform particle size, distributed relatively uniformly throughout the cloud over large areas as found in wide-mesh coating applications . Recently, precise dosing of exact amounts of powder can be achieved using the material feeder described in US Patent No. 5,314,090 by using an elongated brush having an axial length greater than the width of the mesh being coated. Using this apparatus, exact amounts of powder can be fed but not atomized or completely deagglomerated. Meshes can be placed horizontally and the top or bottom or both may need to be coated or placed vertically and one or both sides may need to be coated. Therefore, it is highly desirable to provide an improved powder atomizer, an improved combination of deagglomerator, atomizer and powder feeder and an improved combination of feeder, powder atomizer for use in both vertical and horizontal powder coating applications that produce a cloud of particulate material that is highly uniform in both the transverse and longitudinal directions and in the size of the material in the form of particles and in the particle size distribution of the material. It is also highly desirable to provide an improved powder atomizer, an improved combination of powder feeder and atomizer, and an improved combination of deagglomerator, atomizer and powder feeder that can be used to direct a cloud of particulate material that is uniform both in the transverse and longitudinal directions and in both the particle size and the particle size distribution both on the upper side of the horizontally placed meshes, located below the atomizer and the underside of the horizontally placed meshes located on the atomizer or on opposite sides of the meshes placed vertically. To provide uniformity and versatility, it is highly desirable to provide an improved powder atomizer and an improved combination of powder feeder and atomizer and an improved combination of deagglomerator, feeder and atomizer for these uses in one. variety of applications at a reasonable cost. Finally, it is highly desirable to provide an improved powder atomizer, an improved combination of powder feeder and atomizer, and an improved combination of deagglomerator, atomizer and powder feeder having all of the above desired characteristics.

Brief Description of the Invention Therefore, it is an object of the invention to provide an improved powder atomizer, an improved combination of atomizer and powder feeder and an improved combination of deagglomerator, atomizer and powder feeder. It is also an object of the invention to provide an improved powder atomizer, an improved combination of atomizer and powder feeder and an improved combination of deagglomerator, atomizer and powder feeder that can distribute accurately measured amounts of powder to water streams. Air flowing in a uniformly controlled manner. It is also an object of the invention to provide an improved powder atomizer and an improved combination of powder feeder and atomizer and an improved combination of deagglomerator, feeder and powder atomizer for wide mesh coating operations that can produce deagglomerated clouds of material in Particle shape, with a relatively uniform size, in the cross sections, which are relatively uniform both transversely and longitudinally to the mesh. Also, it is an object of the invention to produce an improved powder atomizer and an improved combination of atomizer and powder feeder and an improved combination of deagglomerator, atomizer and powder feeder that are capable of producing clouds of particulate material, which they are highly uniform both in the transverse and longitudinal directions, in the size of the material in the form of particles and in the distribution of the material in the form of particles. It is also an object of the invention to provide an improved combination of deagglomerator, atomizer and powder feeder and an improved atomizer and an improved deagglomerator for use in powder coating applications both horizontally and vertically that produce a cloud of particulate material. , which is highly uniform in the transverse and longitudinal directions, both in the size of the material in the form of particles and in the particle size distribution of the material. It is also an object of the invention to provide an improved powder atomizer, an improved combination of atomizer and powder feeder, and an improved combination of deagglomerator, atomizer and powder feeder that can be used to direct a cloud of particulate material. , which is uniform both in the transverse and longitudinal directions, and both in the particle size and in the particle size distribution, both on the upper side of the horizontally placed meshes located below the atomizer, and on the underside of the meshes placed horizontally located on the atomizer or combination, or on the opposite sides of the meshes placed vertically or arranged parts in a vertical display. It is also an object of the invention to provide an improved powder atomizer and an improved combination of powder feeder and atomizer, and an improved combination of deagglomerator, feeder and powder atomizer for these uses in a variety of applications at a reasonable cost. Finally, it is an object of the invention to provide an improved powder atomizer and an improved combination of powder feeder and atomizer and an improved combination of deagglomerator, feeder and powder atomizer having all of the above desired characteristics. In the broader aspects of the invention there is provided an improved powder atomizer comprising a cylindrical tray, a resiliently deformable cylindrical member, which is hinged for rotation about an axis within the tray. The tray is mounted coaxially to the element. The element and the tray define a Venturi tube of cylindrical shape between them in which the powder is fed. The Venturi tube has a radially separated inlet and outlet. A means is provided for rotating the element within the tray at speeds in excess of that required to eject the powder from the element by centrifugal force. The element draws ambient air through the Venturi tube, atomizes and de-agglomerates the powder feed at the inlet of the Venturi tube thereby forming a cloud of uniformly flowing particulate material, which is uniform both longitudinally and laterally of this axis. The invention also provides a feeder and atomizer and a deagglomerator combination with the feeder, atomizer combination with a feeder such as that described in U.S. Patent No. 5,314,090 which is particularly useful in wide-mesh coating applications to produce a cloud of material in the form of particles that is uniform both laterally and longitudinally to the mesh and uniform both in the distribution of the material in the form of particles and in the size of the material in the form of particles throughout the cloud that flows uniformly.

Brief Description of the Drawings The above-mentioned and other features and objects of the invention and the manner of achieving them will become more apparent, and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings in where: Figure 1 is a fragmentary perspective view of an improved atomizer of the invention mounted below a conventional hopper in a powder coating process of the upper surface in a wide mesh with a removed end for easy viewing; Figure 2 is a cross-sectional view of the apparatus shown in Figure 1 shown essentially along line 2-2 of section of Figure 1; Figure 3 is a fragmentary perspective view of the improved atomizer of the invention similar to Figure 1, mounted below a hopper feeder, conventional in a wide-mesh bottom surface powder coating apparatus; Figure 4 is a cross-sectional view of the apparatus illustrated in Figure 3 taken essentially along line 4-4 of section of Figure 3; Figure 5 is a fragmentary perspective view of the improved powder atomizer of the invention similar to Figures 1 and 3, mounted below a powder feeder as described in U.S. Patent No. 5,314,090 in a coating process of dust on the left side in a wide mesh, where the mesh or substrate is transported vertically; Figure 6 is a perspective and fragmentary view similar to Figures 1, 3 and 5, of the apparatus similar to that shown in Figure 5 for coating the right side of the same mesh; Figure 7 is a planar, side view of the powder feeder and atomizer of the invention similar to those shown in Figure 5 for coating substrates generally transported horizontally and placed generally vertically in which the powder atomizer is placed angularly with respect to the substrate, the powder conduit is segmented, and the fin is generally cylindrical; Figure 8 is a view of an apparatus similar to Figure 7 of yet another version of the powder feeder and atomizer of the invention shown in Figures 5-7 in which the powder atomizer is generally horizontal and the substrate is placed in general vertical and horizontally transported, but the fin extends spirally from the atomizer upwards; Figure 9 is a fragmentary and perspective view of the atomizer brush and fin removed from the apparatus shown in Figure 8; Y Figure 10 is a fragmentary, cross-sectional view similar to Figure 2 of yet another version of the improved atomizer of the invention assembled in the powder coating process of the upper surface with a removed end for easy viewing.

Description of a Specific Modality With reference to Figures 1 and 2, the improved powder atomizer 10 of the invention is shown as a part of a wide mesh powder coating apparatus 12 mounted on a wide mesh substrate 14 for coating the side 16 of the part upper of the substrate 14. The apparatus 12 includes a powder feeder 18 and an atomizer 10. The powder feeder 18 is shown as a conventional powder hopper 20 that can be provided with a vibrator 22, if desired. The hopper 20 has an opening 24 in the bottom through which the powder is allowed to fall on the atomizer 10 below it. In other specific embodiments, the powder feeder 18 may be an elongated feeder as described in US Patent No. 5,314,090 as shown in Figures 5 and 6 and will be described in detail below. The full description of the specification of U.S. Patent No. 5,314,090 is incorporated herein as transcribed herein. A powder atomizer 10 is shown comprising a tray 26, a fin 50 and a generally cylindrical atomizing element 28 for rotation about a generally horizontal axis 30 in the direction of the arrow 31. The tray 26 is also generally cylindrical in shape. The tray 26 and the element 28 are mounted coaxially to each other. The tray 26 partially encloses the element 28. The element 28 and the tray 26 are separated to define a cylindrical Venturi tube 32 therebetween in which the powder is fed from the feeder 18. The Venturi tube 32 has an inlet 34 directly below of the outlet opening 24 of the feeder 18. The Venturi tube 32 also has an outlet 38 radially spaced from the inlet 34 of the atomizer. The fin 50 is mounted adjacent the brush 28 and extends from the outlet 38 of the Venturi tube to the region to which the agglomerated cloud of particulate material is to be directed. The hopper 20, the tray 26, the atomizing element 28, the venturi tube 32, the inlet 34, the outlet 38 and the fin 50 may all be elongated to extend over the total width or the transverse dimension of the substrate 14, which always it can be the transverse direction. In specific modalities, this transverse dimension has been more than 1.82 meters (6 feet) or equals the transverse dimension of the largest substrate that could be handled, in a specific modality. The atomizer element 28 is secured to the motor shaft 40 via the transmission 42 and is operatively connected to the motor 44. The motor 44 and the transmission 42 rotate the shaft 40 and the element 28 in the direction of the arrow 31 to a speed in excess of the speed required to eject the powder from the element by centrifugal force. The velocity of the element 28 draws air through the Venturi tube 32 at a significantly fast rate of velocity to disburse the powder in the air, to mix the air and the powder in a homogeneous mixture, and to deagglomerate the particles, by the collision of particles to bristles and particles to the wall, to produce particles of relatively uniform size. The velocity of element 28 can also load the particles of the resulting homogeneous cloud, each with a charge of the same polarity. By choosing the material of the bristles of the element 28 which is non-conductive and the particulate material that is non-conductive, a charge of similar polarity can be placed on each of the particles of the particular cloud as it leaves the atomizer of the invention by the process commonly known as the triboelectrification effect. This loading of the material in the form of particles is useful as it helps in the dispersion of the uniform cloud, both longitudinally and laterally thereof as it leaves the atomizer of the invention. This charge also extends the target area over which the cloud is completely uniform in particle size distribution, particle size, and particle density. This triboelectrification effect also has its disadvantages when the tray 26 and the fin 50 are made of conductive materials since the electric charge on the particles induces an opposite electrical charge on the tray 26 and the fin 50, such that the material in the form of particles are attracted to tray 26 and fin 50 and over time produces agglomerates therein. Depending on the conductivity of the particulate material, the particulate material can accumulate and agglomerate at the tip 91 of the tray 26 or the fin 50 to a degree that the particulate, agglomerated material can fall completely either from tip 91 on the substrate below that is being coated. In general, this agglomeration can not be tolerated when the surface of the upper part of a mesh is being coated, since the particulate material that agglomerates sooner or later will fall completely on the surface that is coated, causing imperfections on the coated surface. The agglomeration at the tips 91 can be minimized when manufacturing the tray 26 and the fin 50 of a non-conductive material. However, sometimes, tray 26 and flap 50 are desirably made of conductive material as will be mentioned hereinafter. In the specific embodiment illustrated in Figures 1 and 2, the tray 26 and the fin 50 are made of non-conductive material. In a specific embodiment, this non-conductive material is materials such as polycarbonate, acrylic materials, or acetal. In this specific embodiment, the powder does not agglomerate therein and the tray 26 and the fin 50 do not become loaded by induction, in a manner sufficient for the agglomeration of the powder to occur therein. The experiments indicate that any material having a conductivity in the range of about 1010 to about 1016 will be considered a non-conductive material within the scope of this invention. In another specific embodiment such as illustrated in Figures 1 and 2, the tray 26 and the flap 50 are made of conductive materials such as metal, due both to the structural strength required in the tray 26 and the required surfaces 93, 94. In a specific embodiment, the surface 93 is free of inconsistencies and polished to approximately a surface of 125 rms. Similarly, the surface 94 of the fin is polished to approximately a surface of 125 rms. In a specific embodiment illustrated in Figure 10, the tray 26 for the most part is made of conductive metal such as stainless steel for strength and durability and the tip 91 is made of non-conductive material such as polycarbonate, acrylic, acetal or polyethylene. that structural strength is provided by the metal of portion 95. In this way, tray 26 has a conductive portion 95 and a non-conductive portion 96. The non-conductive portion 96 extends from the tip 91 away from the tip 91 to at least the lowest point 98 in the tray 26 as shown. The portions 95, 96 can be joined together in any manner known to the prior art. Figure 10 shows the tray portions 95 and 96 that are joined with a tongue and groove 99 such that the tray portion 96 can be inserted into the end of the tray portion 94 and slid in that position. In this way, the surface 92 of the tray 26 can be made continuous. In a specific embodiment, the surface 92 is polished to approximately a surface of 125 rms. The flap 50 has an aerodynamic surface 94 extending from the element 28 outwardly therefrom, an end surface 102 away from the element 28, a surface 104 of the near end, spaced close to the element 28 and a surface 106 of the back side . As shown in Figures 1 and 10, the aerodynamic surface 94 can be either curved or planar. The surface 94 is positioned closely adjacent the element 28 and extends outwardly away from the element 28 to direct the cloud outwardly away from the cloud emanating from the exit 38 of the Venturi tube. End 104 may be flat or curved as shown in Figures 1 and 10. In Figure 10, end surface 104 is curved with a radius slightly larger than element 28 and is cylindrical in shape. Both the back surface 106 and the opposite end surface 102 can be flat or curved as desired. In a specific embodiment shown in Figure 10, each of these surfaces are flat and have an angle of repose designed to prevent the accumulation of dust therein, and to recycle or direct the dust that is collected therein away from the surface. surface that is coated. Dust is prevented from accumulating on the surface 94 both by the lack of induced load and by the speed of air moving past the surface 94. On the other hand, the end surface 102 has little movement of air beyond its surface. surface. In this way, the surface 102 has an angle with respect to the horizontal in most modes from about 80 ° to about 100 °. In most applications, the angle of repose of the powder is 80 °. The surface 106 of the back side, similar to the surface 102, has little air flow against the surface. In this way, the surface 106 on the back side will collect the powder therein if the angle of repose is not maximized. However, the dust that is collected on the surface 106 of the back side, if it is angled with respect to the horizontal greater than the angle of repose for the powder, will always be recycled after it collects on the surface as it falls to the surface. and in the rotation element 28. In a specific embodiment, the surface 106 has an angle with respect to the horizontal from about 45 ° to about 70 ° with the horizontal. With reference to Figures 1 and 2, it is shown Aa surface 94 that is curved. The surface 102 extends from the curved surface generally perpendicular thereto. The rear surface 106 extends from the hopper 18 to the fin 50 at an incline with the recirculation openings 110 therein. Figures 3, 4, 5 and 6 similarly have the surface 94, the surfaces 106 on the back side and the surfaces 78 generally perpendicular as shown. Recirculation openings 110 are placed in the surface 78 as shown. Element 28 functions both as a blower rotor with tray 26 to direct air and dust entrained therein through venturi 32 and as a powder carrier as described in U.S. Patent No. 5,314,090. The speed of rotation of the element 28 and the separation of the element 28 from the tray 26 has a ratio that both move the required air through the Venturi tube 28 fast enough to atomize the powder that is fed into the inlet 34 of the Venturi tube and disperses The dust is uniformly distributed in a cloud that emerges from exit 38 of the Venturi tube. In specific embodiments, the outlet 28 of the atomizer is a brush as described in U.S. Patent No. 5,314,090. The brush 28 may be any cylindrical element having a center and radially extending bristles of any type. The bristles can be densely packed or separated, arranged in a design or arranged randomly, long or short, thin or thick, relatively rigid or relatively flexible, and made of materials ranging from metals to plastics to natural filaments. The diametral size of the center and the length of the bristles may also vary. The bristles of choice depend on the function of the brush and the type of powder that is atomized. If the atomizer is being used to disperse large amounts of dust in a small amount of air, the brush may have to carry some powder between the bristles before atomization. In these cases, the length of the bristles must be greater than usual to increase the carrying capacity of brush dust between the bristles. When the used powder tends to agglomerate or does not flow easily in the atomizer, the flexible bristles have the advantage that the bending of the bristles will help in the addition of movement and the deagglomeration of the powder. If a reduction in the size of the material in the form of particles is desired, a brush with rigid bristles is required. The length and material of the bristles will determine the life of the brush in any particular application. The charge on the individual particles of the cloud of particulate material left by the atomizer 10 of the invention will generally increase in an increase in the rotation speed of the element 28, in the decrease in the conductivity of the material of the bristles and in a decrease of the • Conductivity of the material in the form of particles. In most applications, the performance of the brush element 28 can also be altered and finally adjusted by varying the speed at which the atomizer element 28 is rotated. In specific embodiments, in which deagglomeration and reduction of particle size are required, the brush 28 is selected with bristles of specific materials, having a particular transverse diameter, and a particular longitudinal length. The bristles may have a circular cross section or a rectangular cross section. When it is the rectangular cross section, the resilient flexibility of the bristle in the direction of rotation and the direction transverse to it can be varied. This is important, since the deagglomeration and reduction of the particle is believed to be dependent on particle-to-bristle collisions in which the bristle hits the particle and then moves to one side, transversely to the direction of movement, to allow the particle to be impacted in another sow. In this way, the denser the bristles are packed, the more particle-to-sow collisions will occur. The ratio of the length to the transverse dimension in the direction of rotation and the rotational speed of the brush determine the magnitude of the impact between the particle and the brush. The ratio of the length to the transverse dimension of the direction of rotation and the density of the bristles and the rotational speed of the brush determine the number of impacts that will occur between the particles and the bristles.

In specific embodiments, the bristles may include natural bristles, bristles of synthetic polymers and metal bristles. The lengths of the bristles vary from relatively short bristles to relatively long bristles. The transverse dimensions of the bristles vary from about 2 to 3 times the size of the particles that are atomized to the transverse dimensions of fifty (50) times the largest transverse dimension of the particles that are atomized. This in a practical sense, the bristles are limited to those that have the largest transverse dimension from about 4 to about 15,000 microns, and the length from a few centimeters to a number of meters. While the effect of the longitudinal length ratio to the transverse dimension of the bristles in the reduction of the particle size and the deagglomeration capacity of the element 28 is well established, the overall diameter of the brush 28 seems to have less effect on the deagglomeration and the reduction of the particle size. By choosing the elements 28 of larger diameters, the longitudinal length of the Venturi tube in the direction of the air flow increases, and in this way the number of collisions between the particles and the bristles increases. However, the impact force between the bristles and the collision particles is determined by the hardness of the bristle and the longitudinal length ratio and the transverse direction of the bristle as mentioned above. In this way, increasing the diameter of the element 28 and maintaining the same length-to-width ratio of the bristles specifically increases the number of particle collisions, not the type of collisions that occur. In this way, the focus in most applications is on the ratio of length to the transverse dimension of the bristles and the material properties of the bristle before the diameter of the brush 28. However, in specific embodiments, the relationship length to the transverse dimension of the bristles varies from approximately 200 to 1 to approximately 800 to 1, the length of the bristles varies from approximately 1.27 cm (1/2 inch) to approximately 12.7 cm (5 inches), the transverse dimensions of the bristle in the direction of rotation vary from about 0.00254 cm (0.001 inches) to about 0.157 cm (0.062 inches), the transverse dimensions of the bristle in directions transverse to the direction of rotation vary from about 0.00254 cm (0.001 inches) up to approximately 0.157 cm (0.062 inches), and the length ratio of the bristle to the transverse dimension varies from approximately 200 to 1 to about 800 to 1. In specific embodiments, the tray 26 and the element 28 and the flap 50 can be lengthened for the wide-mesh coating processes or can have length-to-diameter ratios of the element 28 of less than 1, as is desired In specific embodiments, the thickness of the Venturi tube or the distance between the element 28 and the tray 26 is from about 0.00254 to about 0.254 cm (0.001 to about 0.100 inches) and the element 28 is driven at speeds from about 700 to about 4,000 RPM depending on the diametral size of the rotor and the proportion in kilograms per minute the powder is desirably atomized by the improved atomizer of the invention. Additionally in those embodiments, the element 28 is separated from the ends of the tray that is removed in the Figures to improve the view of the rotor element 28 and the Venturi tube 32 and is separated from the fin 50 at a distance from about 0.00254 to approximately 0.051 cm (0.001 to approximately 0.020 inches). In these specific embodiments, the powder having a particle size from about 2 to about 300 microns can be atomized into a uniform cloud of the particulate material having a relatively uniform particulate material size., and uniformly distributed throughout the cloud both in the direction of the flow and the transverse directions of the same. The hopper 20 can be any conventional hopper for use with powder material. The hopper 20 can be geometric as shown in Figures 1 and 2 or can be asymmetric having for example a vertical wall and an angular wall both vertically and horizontally. It is highly preferable that the walls of the hopper 20 have both an angle with the horizontal greater than the angle of repose with respect to both the material of the walls of the hopper and the powder material being fed. The hopper 20 is mounted independently of the powder atomizer 10 and can be mounted in springs (not shown) and provided with a vibrator 22 as mentioned above. The opening 24 of the bottom of the hopper 20 is shown to be placed over the inlet 32 of the Venturi tube. The inlet 32 of the Venturi tube in a specific embodiment can be covered to capture essentially all of the dust that falls from the hopper 20 in the atomizer 10. The outlet 38 of the Venturi tube 32 and the fin 50 are directed and released to distribute a cloud fluid of particulate material dispersed homogeneously throughout its volume of air in the inlet area 46 of a conventional electrostatic coater apparatus 48. The direction or launch of the cloud towards the objective is achieved by using the fin 50 and the conventional gas flow techniques of the Coanda effect. The flap 50 may also serve the purpose of enclosing the atomizer element of the upper region to keep the atmosphere around the atomizer as dust-free as possible. Totally surprising, the cloud leaving the outlet 38 of the Venturi tube is not thrown from the rapid rotation element 28 as would be expected. In severe contrast, the homogeneous cloud of the aspirated particulate material appears to follow the arcuate surface of the element 28 circumferentially around the element at least 90 ° to as much as 360 °. In this way, it is necessary to provide a fin to prevent the cloud from following element 28.

The flap works not only to remove the cloud from element 28, but also to direct the cloud as desired to a desired region. Thus, in all embodiments, the leading edge of the fin needs to be virtually adjacent to the circumference of the element 28. In practical experience, the element 28 seems to work well being separated from the brush distances in general as close as may be possible. A totally surprising case in the operation of the atomizer 10, is that the area between the powder atomizer 10 and the coating machine 48 does not need to be totally closed since the cloud of the particulate material emanating from the Venturi tube will continue in generally first the arcuate route of the rotation of the element 28 and then second the surface of the fin 94 and it will not disperse throughout the entire room surrounding the atomizer in an uncontrolled condition as experienced with other powder atomizer designs. The atomizer 10 appears to impart a significant velocity to the cloud such that the Coanda effect dominates the effect that substantially static ambient air has on the cloud of particulate material.

Once the cloud is directed to the entrance area 46 of an electrostatic coating machine 48, the cloud will be under the influence of the electric field and the ionization of the electrodes 52 of the coating machine and the flow of the carrier gas. the cloud through the coating machine 48. In a specific embodiment, the coating machine 48 can be any of those described in U.S. Patent No. 5,279,863, the description of the specification of which is incorporated herein by reference as being reproduced in the present word by word. In a specific embodiment, the flap 50 can be secured either to the hopper 20 and vibrate with it to minimize dust accumulation therein, or is independently supported or secured to the tray 26. With reference to Figures 3 and 4, there is shown an atomizer 10 and an apparatus 12 for use in the coating of the bottom side 53 of a substrate 14. The powder feeder 18 is also in the form of a hopper 20. In Figures 3 and 4, the hopper 20 is shown without the vibrator 22 and with a transport device 54 operatively positioned with respect to the hopper 20, to keep the hopper 20 full of dust. Similarly, in other embodiments, the embodiment of Figures 1 and 2 can be provided with a conveyor 54 and used with or without a vibrator 22. The speed at which the conveyor 54 is operated should be coordinated with the speed at which the conveyor 54 is operated. which atomizer 10 is operated, so as to maintain a continuous and adequate flow from the conveyor 54 through the hopper 20 and through the atomizer 10 and up to the coating apparatus 48. In this mode, the hopper 20 and the atomizer must be identical as described above. However, the flap 50 is positioned adjacent the outlet 38 to extend between the tray 26 to the entrance area 46 of the coating machine 48. The fin 50 can be both formed and positioned in accordance with conventional gas flow technology. The cloud of the particulate material, discharged homogeneously throughout, is removed from the element 28 and fed into the inlet 46 of the coating machine 48, at which time the cloud will be under the influence of the electric field of the machine 48, the movement of the cloud through the machine 48 is also controlled by the discharge and gravity of the machine as is conventional.

Surprisingly, very little dust was not de-agglomerated by the atomizer to a powder size in which the powder would be completely driven through the air. Essentially, all powder feed to the atomizer 10 by the powder feeder 18 was completely de-agglomerated to a desired particle size and atomized and essentially no dust was driven through the air and exited through the powder drain 56 in the bottom edge of it. In this way, in most embodiments, the dust drainage 56 for removing large particles that can not be maintained by air in the cloud leaving the atomizer 10 is believed to be unnecessary and superfluous in consideration of the structure of the atomizer 10. In all applications, the substrate 14 is moved via conveyor techniques in relation to the atomizer 10, the powder feeder 18 and the coating machine 48. The direction of travel of the substrate, i.e., if the bare substrate moves away from the atomizer 10 or towards the atomizer 10, depends on the coating process. As with other electrostatic coating processes, it may be more desirable to cause the bare substrate 14 to be impacted with the more concentrated cloud emanating directly from the atomizer 10 of the invention. In other coating processes, it may be advantageous to have to increase the powder concentration of the cloud as the coated substrate 14 reaches the atomizer 10. In general there is no interest in the conductivity of the tray 20 and the fin 50 in the embodiment illustrated in Figures 3 and 4 since the embodiment is shown adapted to coat the bottom surface of a substrate. Since the entire apparatus is located below the surface to be coated, any agglomeration that falls completely from the apparatus will not affect the surface coating. With reference to Figures 5 and 6, the hopper is replaced with the powder feeder 60 described in US Patent No. 5,314,090. The powder feeder 60 of this patent as shown is capable of feeding quantities of powder reproducibly and accurately measured to the atomizer 10 of the invention. In this way, the powder feeder 60 can be used where the control of powder feed to the atomizer is more critical to the process and more control is required as much as possible using a hopper 20 as described above. The powder feeder 60 is fed by a hopper 62 which functions as a powder container for the powder feeder 60. The hopper 62 can, in a specific embodiment, be identical to the hopper 20 and be equipped with, or used without a vibrator 22. As shown, the hopper 62 has a bottom opening 24 that is emptied into a housing 64 in the which a resiliently deformable element or brush 66 articulates for rotation in the direction of the arrow 67. The element 66 secures a shaft 68 and articulates on opposite walls (not shown) of the housing 64. One end of the shaft 68 is connected to a variable speed 70 motor. The housing 64 has a ventral portion 72, a bottom portion 74, a portion 76 of the upper portion, and a pair of side portions 78. The housing 64 completely closes the element 66. The element 66 is generally cylindrical. The housing 64 can be made of plastic or any other suitable non-conductive material. Other embodiments have the housing 64 made of transparent plastic material or have an access door in the housing 64 (not shown) so that during operations, observations and adjustments can be made. The element 66 is placed in the housing 64 to obstruct the opening 24 of the hopper. In most specific embodiments, the element 66 is preferably a brush having a plurality of bristles 80 arranged with uniform density around the center 81 to extend radially therefrom. The bristles 80 can be filaments of natural origin or filaments of any suitable material, so that the brush 66 is able to "concentrate" the powder so that it flows from the hopper 20 through the opening 24 of the bottom. The bristles 80 should be of suitable length and dimension, where at a selected rotational speed, the brush 66 allows the powder of the hopper 20 to penetrate the bristles 80 in a precise manner, be transported by the brush 66 as it rotates, and they are distributed in a measured quantity through the outlet orifice 82 in the bottom 74 towards the atomizer 10 of the invention. As described in U.S. Patent No. 5,314,090, the speed at which the element 66 is driven is always below that required to eject the powder material from the element 66 by centrifugal force.

The flow rate of the powder from the hopper 20 through the outlet orifice 82 is controlled, inter alia, by the rate of speed that the brush 66 is rotated in the direction of the arrow 67, the diameter of the brush 66, the dust capacity of the brush 66 and the size of the opening 24. The dust transport capacity of the brush 66 is controlled by the length and density of the bristles 80. The powder flow rate from the hopper 20 through the feeder 60 contributes to the total powder flow rate to the atomizer 10. The outlet orifice 82 of the feeder 60 is positioned so that the exiting powder falls into the inlet 34 of the Venturi tube 32 in the same manner as described above with regarding the placement of the opening 24 of the bottom of the hopper 20 as shown in Figures 1-4. As shown in Figures 5 and 6, housing 64 can be provided in combination with tray 26 and flap 50 to form a common housing for both element 66 and element 28. This housing would extend tray 26 upwardly. to couple the hopper 62 of the material feeder 60 and the fin 50 to enclose the element 66 and to define with the tray 26 both the holes 3482, to segregate the elements 66, 28 and to properly define the inlet 34 and the outlet 38 of the Venturi tube 32. In both Figures 5 and 6, the substrate 44 can be moved either towards the atomizer 10 or away from the East. Additionally, the outlet 38 of the atomizer 10 and the cloud of the particulate material can be deflected downwardly as shown in Figures 5 and 6 or upward as desired. This choice usually depends on the particle size and the particle size distribution of the cloud, or it is preferable or not to make gravity assist in depositing larger particles on the substrate. In general, there is no interest in the conductivity of tray 20 and flap 50 in the embodiment illustrated in Figures 5 and 6, since the embodiment is shown adapted to coat a vertically placed substrate. Since the entire apparatus is located on one side of the surface to be coated, an agglomeration that falls completely out of the apparatus would not affect the surface coating. In the embodiments shown in Figures 1-6, several variables are present in the structure. The tray 26 and the element 28 can be of any diametral size. The amount of powder that can be atomized by the atomizer 10 is larger, the larger the element 28 and the tray 26, the greater the venturi 32, and the greater the volume of air in which the powder can be atomized . If the element 28 is a brush, the length of the bristles becomes a variable. However, since the brush 28 rotates at a speed above the speed at which the powder will leave the atomizer due to the centrifugal force, the length of the bristles is not critical. However, the distance between the brush and the tray is critical and a function of the element 28 and the speed at which it travels. In a specific embodiment, this distance varies from about 0.0127 to about 0.254 cm (0.005 to about 0.100 inches). The element 28 traveling at a speed sufficient to eject the particles being atomized from the element 28 by centrifugal force must be sufficient to give the air in the turbulence and sufficient velocity of the Venturi tube to atomize the dust in the air. In this way, the distance between the element 28 and the tray 26 can be larger if the speed of the element 28 is larger and vice versa. In specific embodiments, the element 28 preferably has a diameter of 5.08 cm (2 inches) or more, or is larger and is driven at speeds of approximately 700 to 4,000 rpm. The vertical distance from the opening 24 of the bottom of the hopper and the inlet 34 of the Venturi tube can also vary. This distance can be any distance that dust can fall and efficiently feed into the Venturi tube. In specific modalities, this distance has varied between 2.54 cm to 1.82 meters (one inch to 6 feet) or more. The radial positions may also vary between the inlet 34 of the Venturi tube and the exit 38 of the Venturi tube. In specific embodiments, this distance has been from about 180 ° to about 45 °. In the embodiments illustrated in Figures 5 and 6, in which the atomizer 10 of the invention is combined with the material feeder of US Patent No. 5,314,090, the ratio of the diameters between the element 66 and the element 28 may be any number, in most of the specific modalities, the ratio is equal to or greater than 1, similarly, the ratio of the speeds is kept better as high as possible. The distance between the axes of the elements 28 and 66 measured from tree to tree is usually just a diameter, but can be anything from about a few centimeters to 1.82 meters (6 feet) or more. In all embodiments of the invention, the powder exiting the Venturi tube 32 follows the contour of the fin 50 and is thus directed to a target. The dust that passes through the Venturi tube is de-agglomerated, atomizes and triboelectrifies if the bristles of the brush are non-conductive, so that when it leaves the Venturi tube 32, the powder is loaded with each of the material in the form of powder particles having a similar charge. In this way, the powder exiting Venturi tube 32 is forced to uniformly disperse both transversely and longitudinally of the substrate both by the turbulent flow of the air in which the particulate material is atomized and by the particle repellent forces. similarly charged. The cloud of particulate material follows the curvature of the fin 50 due to the velocity of the cloud against the fin. In specific embodiments, in which the powder atomizer is positioned from about 10.16 to 15.24 cm (4 to 6 inches) from a substrate, it has been observed that the cloud of the particulate material can be directed to the substrate in a relatively uniform on about a wide design of 5.08 to 15.24 cm (2 to 6 inches), both uniformly longitudinally and transversely of the substrate. In positions outside the peripheral margins of that design, the uniformity in the concentration of the material in the form of cloud particles falls in a completely dramatic way. The previous design in the modalities illustrated in Figures 1 and 2 where the cloud of the particulate material is directed to a target below the atomizer where gravity works with the flow of the cloud to distribute the material in the form of particles, atomized in the lens, the design of 5.08 to 15.24 cm (2 to 6 inches) described above can extend approximately a design of 10.16 to 25.4 cm (4 to 10 inches). Similarly, when the gravitational forces in the cloud of the particulate material are opposed to the movement of the cloud of the material in the form of particles leaving the venturi tube 32 as in the modalities illustrated in Figures 3 and 4, the design from 5.08 to 15.24 cm (2 to 6 inches) described above can decrease to approximately a design from 2.54 to approximately 7.62 cm (1 to approximately 3 inches). In any case, due to this phenomenon, there is a problem in the uniform coating of vertically placed substrates that are at distances beyond 10.16 to 15.24 cm (4 to 6 inches) from the atomizer of the invention. For example, the 30.48 cm (12 inches) tall uniform coating of a vertically placed substrate moving horizontally using the atomizer of the invention located adjacent to the lower limit thereof would only cover approximately 10.16 to 15.24 cm (4 a). 6 inches) of the substrate evenly and the dust deposit at 15.24 cm (6 inches) from the top of the substrate would be significantly less than the dust deposit at 15.24 cm (6 inches) from the bottom of the substrate. With reference to Figure 7, a combination of atomizer and powder feeder is shown for coating horizontally placed, vertically placed carrier substrates of transverse dimensions greater than about 5.08 to 10.16 cm (2 to 4 inches). As shown in Figure 7, a powder feeder 60 having the entire structure of the powder feeder 60 described above is mounted higher than the substrate 84. Positioned below the feeder 60 is the atomizer 10 of the invention with the element 28 mounted in a separate relationship to the substrate 84, but angularly positioned both vertically and horizontally as shown. A powder conduit 86 extends from the bottom opening 82 to the inlet 34 of the Venturi tube through which dust falls from the powder feeder 60 into the venturi 32 formed by the tray 26 surrounding the brush element 28 . The fin 50 extends from the exit 38 of the Venturi tube to the substrate 84. The fin 50 and the tray 26 and the element 28 each separate uniformly from the substrate 84 with the distance between the exit 38 of the Venturi tube and the substrate 84, in a specific embodiment which is from about 10.16 to about 15.24 cm (4 to about 6 inches) over the entire axial length of the atomizer 10. Since the powder feeder 60 and the atomizer 10 can be of any axial length, the embodiment illustrated in Figure 7 can be used to coat horizontally transported sheet material, placed vertically or an array of parts hanging from a vertically extending conveyor, transported horizontally of any transverse dimension or height. In general, there is no interest in the conductivity of tray 20 and flap 50 in the embodiment illustrated in Figure 7 since the embodiment is shown adapted to coat a vertically placed substrate. Since all the. Apparatus is located on one side of the surface to be coated, an agglomeration that falls completely off the apparatus would not affect the surface coating. With reference to Figures 8 and 9, another version of the improved deagglomerator, atomizer and powder feeder combination of the invention is shown for use with vertically placed and horizontally transported substrates of the type described above. In this embodiment, the feeder 60 is shown to be positioned on the atomizer 10, a powder conduit 86 extending from the outlet orifice 82 of the feeder 60 and the inlet 34 of the Venturi tube 32, and the atomizer 10 is equipped with a fin 50 which is in the form of a spiral, having a spiral-shaped conducting edge 88 for removing the cloud of particulate material from the element 28, a cylindrical cross section and a spiral-like distant edge 90 which crosses its full length, is placed from about 10.16 to about 15.24 cm (4 to about 6 inches) from the substrate to be coated. This embodiment is useful only for substrates having transverse dimensions or a vertical height less than the vertical height of the spiral-shaped fin 50 approximately plus or minus 2.54 to 15.24 cm (1 to 6 inches). While in the specific embodiments, the feeder 60 may be on the substrate 84 or on one side of the substrate 84, the atomizer 10 should always be located adjacent the bottom edge 92 of the substrate 84 and the spiral-shaped fin 50 should extend over the full vertical dimension of the substrate 84 as shown. Figure 9 is a perspective view of the tray 26, the brush element 28 and the spiral-shaped fin 50 of the atomizer 10 illustrated in Figure 8, to better show the shape of the fin 50 and its relation to the outlet 38 of the Venturi tube and the entrance 34 of the Venturi tube. The powder duct 86 is illustrated in Figure 7 as a segmented duct, which generally has separate and generally parallel vertical walls. In Figure 8, the conduit 86 is illustrated as being a non-segmented conduit, having no divisions or walls between the opposite ends. These ducts are interchangeable depending on the dimensions of the substrate and the properties of the powder that is atomized. In general there is no interest in the conductivity of the tray 20 and the fin 50 in the embodiment illustrated in Figures 8 and 9 since the embodiment is shown adapted to coat vertically placed substrates. Since the entire apparatus is located on one side of the surface to be coated, an agglomeration that falls completely out of the apparatus would not affect the surface coating. In operation, the powder in the tray 20 is fed through the opening 24 of the bottom to the inlet 34 of the Venturi tube 32 in the modes illustrated in Figures 1 and 4. The flow of powder in the Venturi tube 32 can be control by selectively choosing the opening 24 of the bottom to be of a specific size or controlling the action of the vibrator 22. As the powder enters the Venturi tube 32, the element 28 draws carrier gas through the venturi tube at a relatively fast speed in a turbulent manner. The element 28 atomizes all the powder that comes into contact with the element as the element 28 is rotating at a speed in excess of that necessary to throw the powder therefrom by centrifugal force. Depending on the particulate material and stiffness of the bristles 80 of the element 28, the size of the particulate material can also be reduced in the atomizer 10 by varying the speed of the brush, as desired. The powder dispersed in the carrier gas in the form of a cloud comes out from the outlet 38 of the Venturi tube. This cloud is generally homogeneous in the amount of dust per unit volume of carrier gas, but also in the particle size distribution and particle distribution both in the direction of the gas flow and in the directions transverse to it. . Additionally, the particle size distribution is generally uniform throughout the cloud since the turbulence of the carrier gas within the Venturi tube is sufficient to deagglomerate the powder. In any case, by the appropriate choice of the velocity of the element, the powder of relatively uniform size can be distributed in a relatively uniform manner throughout the cloud in both the particle density and the particle size distribution.

Very little mechanical work is done in the powder using the vacuum cleaner 10 of the invention by the element 28 or the centrifugal forces. When the powder feeder 60 is used with the vacuum cleaner 10 of the invention, precise amounts of powder can be metered into the vacuum cleaner 10. By controlling the flow of the powder from the hopper 62 to the feeder by a conventional means and by controlling the speed of the element 66, accurately measured amounts of powder can be fed into the vacuum cleaner. The vibration and gravity move the powder from the hopper 62 to the element 66 that transports the powder to the outlet orifice 82 with very little mechanical work done in the powder. In the specific embodiments, in which the element is a brush, the powder is fed into the bristles 80, the brush rotates and releases the powder by gravity through the outlet orifice 82.

Therefore, when selecting a vibration speed (if a vibrator 22 is used), a housing having an outlet opening 24 of a specific size, a brush 66 and a rotational speed, precise amounts of powder can be delivered to the vacuum cleaner 10 of the invention. As the brush element 66 rotates, the element is exposed to dust in the hopper 62 and is filled with dust between the bristles and rotated over the outlet orifice 82 through which the element 66 discharges the powder carried by the element. . Once the powder is discharged from the powder feeder 18 or 60 into the aspirator 10, the powder enters the Venturi tube 32 through the inlet 34 of the Venturi tube and engages with the fast moving carrier gas which is drawn through the Venturi tube by the element 28. The element 28 throws all the powder in the carrier gas by centrifugal force and moves the carrier gas in a turbulent manner through the Venturi tube 32 to the outlet 38 of the Venturi tube. Once the powder leaves the outlet 38 of the venturi, the cloud of the particulate, uniform material follows the curvature of the element 28 until it is removed from the element 28 by the fin 50 and guided by the fin 50 in accordance with the gas flow principles, conventional towards the inlet 46 of the coating machine 48. As shown in Figures 1 and 2, the cloud from the outlet 38 can be directed downwardly by the vacuum cleaner 10 of the invention to coat the top side of the substrate. As shown in Figures 3 and 4, the aspirator 10 can direct the cloud of particulate material from outlet 38 of the Venturi tube upward to coat the bottom side of a substrate. The extracts can be coated on both sides, either oriented horizontally or vertically as shown in Figures 1-4, Figures 5 and 6 and Figures 7-9, respectively. The powder performance of the atomizer 10 of the invention in all modes is controlled by the speed of the powder that is fed from the Venturi tube 32 by the powder feeder 20 or 60. The density of the particulate material of the cloud generated by the atomizer 10 of the invention is a function of the amount of powder fed into the atomizer 10 and the amount of the carrier gas entrained through the Venturi tube. In most practical applications, the amount of carrier gas entrained through the Venturi tube is controlled by the distance between the tray 26 and the element 28 and the rotation speed of the element 28. The smaller the distance, the smaller the gas It will be transported. The greater the distance, the more gas will be transported. Similarly, the amount of powder fed into the Venturi tube 32 by the powder feeder is mainly, in the case of a hopper 20, a function of the size of the bottom opening 24 and the flow of powder therethrough, or in the case of the feeder 60, the rotation speed and capacity of the element 66. The improved atomizer of the invention produces a relatively uniform cloud of particulate material and directs that cloud in an electrostatic coating apparatus either in a direction towards up or in a downward direction as desired. By the invention, an improved powder atomizer and an improved combination of atomizer and powder feeder and an improved combination of deagglomerator, atomizer and powder feeder are provided for all powder coating operations. The improved powder atomizer of the invention is particularly useful for wide-mesh coating operations since it can produce clouds of particulate material with a relatively uniform size in the cross-sections taken longitudinally of the mesh and transversely thereof and they can be highly uniform in both the particle size of the material and the particle size distribution of the material. By using a feeder of particulate material as described in U.S. Patent No. 5,314,090, quantities of the particulate material, measured in a highly accurate manner, can be atomized and placed on substrates of any transverse dimension, either placed horizontally, vertically or at an angle between them by the improved atomizer, atomizer, feeder combinations and deagglomerator, atomizer and feeder combinations of the invention. The improved powder atomizer, the improved atomizer and powder feeder combination and the deagglomerator, atomizer and powder feeder of the invention can be used to coat both the top and bottom sides of horizontally placed meshes and both sides of the meshes placed vertically. The improved powder atomizer; the atomizer and feeder; and deagglomerator, atomizer and feeder of the invention can be used to power powder coating apparatus at a reasonable installation and maintenance cost. Finally, the improved atomizer; the atomizer and feeder; and the deagglomerator, atomizer and feeder of the invention can be provided in the form having all the features described above. While a specific embodiment of the invention has been shown and described herein for purposes of illustration, the protection given by any patent that may be issued in this application is not strictly limited to the described embodiment; rather, it extends to all structures and arrangements that fall completely within the scope of the claims appended hereto.

Claims (50)

1. A powder atomizer, characterized in that it comprises a tray, a cylindrical element, the element that is articulated for rotation about an axis, the tray that is cylindrical and is placed coaxially to the element, the tray that partially encloses the element, the element and the tray defining a cylindrical Venturi tube between them on which powder is fed, the Venturi tube having a radially spaced inlet and outlet, a means for rotating the element within the tray at speeds in excess of the required speed to eject dust from the element by centrifugal force, the element that drags gas through the Venturi tube and atomizes the powder fed into the inlet to produce a uniform cloud of particulate material, and a means to minimize the electrical charge in the tray and the resulting agglomeration of the powder at the outlet.

2. A powder atomizer, characterized in that it comprises a tray, a cylindrical element, the element that is articulated for rotation about an axis, the tray that is cylindrical and is placed coaxially to the element, the tray that partially encloses the element, the element and the tray defining a cylindrical Venturi tube between them on which powder is fed, the Venturi tube having a radially separated inlet and outlet, a means for rotating the element within the tray at speeds in excess of the required speed to eject dust from the element by centrifugal force, the element that draws gas through the Venturi tube and atomizes the powder fed into the inlet to produce a uniform cloud of particulate material, the tray adjacent to the exit that is made of non-conductive material.

3. The atomizer according to claim 2, characterized in that the non-conductive material has a conductivity of about 1010 to about 1016 ohm-centimeters.

4. The atomizer according to claim 2, characterized in that the non-conductive material is chosen from the group of materials consisting of polymeric, structural materials.

5. The atomizer according to claim 2, characterized in that the non-conductive material is chosen from the group of polymeric, structural materials consisting of polycarbonates, acrylics, acetals and polyethylenes.

6. The atomizer according to claim 2, characterized in that the tray adjacent to the outlet is pointed, thereby defining an edge adjacent to the element, the tray having a surface that depends from the edge.

7. The atomizer according to claim 6, characterized in that the surface that depends on the edge is generally perpendicular.

8. The atomizer according to claim 2, characterized in that the tray is made of non-conductive material from the outlet to at least the lowest point of the venturi tube.

9. The atomizer according to claim 1 or 2, characterized in that it further comprises a fin separated from the element from about 0.00254 to about 0.051 cm (0.001 to about 0.020 inches), the fin having a surface extending from the element upwardly away of the element, the surface that is aerodynamically smooth, the surface having an angle with respect to the horizontal, the fin having an end surface separated from the element having an angle with respect to the horizontal surface greater than the angle of repose, the fin having a surface of the rear side having an angle with respect to the horizontal greater than the angle of repose.

10. The atomizer according to claim 9, characterized in that the non-conductive material of the fin has a conductivity of about 1010 to about 1016 ohm-centimeters.

11. The atomizer according to claim 9, characterized in that the angle of the aerodynamically smooth surface and the rear side surface is less than 90 °, the aerodynamically smooth surface is formed and separated to direct the cloud away from the element, and comprising also a separate fin target from approximately 2.54 to 15.24 cm (1 to 6 inches), the aerodynamically smooth surface that directs the cloud towards the target.

12. The atomizer according to claim 9, characterized in that the angle of the aerodynamically smooth surface is less than 90 °.

13. The atomizer according to claim 9, characterized in that the angle of the surface separated from the element is approximately 90 °.

14. The atomizer according to claim 9, characterized in that the angle of the surface of the rear side causes any accumulation of dust in it to fall from the fin towards the element and thus be recycled.

15. The atomizer according to claim 9, characterized in that the angle of the rear side surface is from about 45 ° to about 70 °.

16. The atomizer according to claim 9, characterized in that the angle of the aerodynamically smooth surface is from about 45 ° to about 70 °.

17. The atomizer according to claim 9, characterized in that the fin has a surface cylindrically formed adjacent to the element, this surface is minimized.

18. The atomizer according to claim 9 or 40, characterized in that the objective is elongated, the element and the tray are parallel to the elongation of the objective, the fin having edges that are spirally shaped to extend the full transverse width of the objective.

19. The atomizer according to claim 9 or 40, characterized in that the objective is elongated, the element, the tray and the fin extend transversely to the objective.

20. The atomizer according to claim 1 or 2 or 31, characterized in that the inlet is divergent.

21. The atomizer according to claim 1 or 2 or 31, characterized in that the outlet is divergent.

22. The atomizer according to claim 1 or 2 or 31, characterized in that the element is rotated at a speed of about 700 to about 4,000 rpm.

23. The atomizer according to claim 1 or 2 or 31, characterized in that the Venturi tube has a uniform thickness between inlet and outlet of about 0.00254 to about 0.051 cm (0.001 to about 0.020 inches.

24. The atomizer according to claim 1 or 2 or 31, characterized in that the element has a diameter greater than about 5.08 cm (2 inches).

25. The atomizer according to claim 1 or 2 or 31, characterized in that the size of the material in the form of powder particles ranges from about 2 to about 300 micras

26. The atomizer according to claim 1 or 2 or 31, characterized in that the element is a brush.

27. The atomizer according to claim 1 or 2 or 31, characterized in that the powder that is fed into the Venturi tube has a larger size than the powder leaving the Venturi tube.

28. The atomizer according to claim 1 or 2 or 31, characterized in that the powder is chosen from the group of powders consisting of thermoplastic and thermosetting organic polymers, organic materials, and combinations thereof.

29. The atomizer according to claim 1 or 2 or 31, characterized in that the cloud is a triboelectrified cloud in a relatively uniform manner of particulate, powdered materials, uniformly dispersed in a slowly moving carrier gas stream.

30. The atomizer according to claim 1 or 2 or 31, characterized in that the target is displaced radially from the inlet from about 45 ° to about 240 °.

31. A powder atomizer, characterized in that it comprises a tray, a cylindrical element, the element that is articulated for rotation about an axis, the tray that is cylindrical is placed coaxially to the element, the tray that partially encloses the element, the element and the tray defining a cylindrical Venturi tube between them in which the powder is fed, the Venturi tube having a radially separated inlet and outlet, a means for rotating the element inside the tray at speeds in excess of the speed required to eject dust from the element by centrifugal force, the element that draws gas through the Venturi tube and atomizes the dust fed into the inlet to produce a cloud of particulate material, the element that is chosen to maximize the collisions from particle to particle and from particle to element, to deagglomerate and thereby reduce the particle size of the powder that is fed from the Venturi tube.

32. The atomizer according to claim 31, characterized in that the element is a brush having bristles, the bristles are chosen with a transverse dimension and a length and physical properties together with the physical properties of the powder and is fed to the Venturi tube to de-agglomerate and reduce the size of the powder.

33. The atomizer according to claim 32, characterized in that the bristles of the brush are resilient, the bristles are resiliently flexible in the collision between the bristles and the particles, thereby increasing the deagglomeration and reduction in particle size of the powder.

34. The atomizer according to claim 31, characterized in that the bristles are essentially cylindrical having a length to diameter ratio of about 10 to 1 to about 5,000 to 1.

35. The atomizer according to claim 31, characterized in that the bristles are generally in the form of a parallelogram in their cross-section and in which the bristles have a longitudinal length-to-length ratio of about 200 to 1 to about 800 to 1.

36. The atomizer according to claim 31, characterized in that the bristles have a parallelogram cross section which in the direction of rotation, the bristles are thicker than in the directions transverse to it, the bristles which are stiffer and less flexible in the direction of rotation and in directions transverse to it.

37. The atomizer according to claim 31, characterized in that the bristles have a length from about 1.27 to about 12.7 cm (half an inch to about 5 inches).

38. The atomizer according to claim 31, characterized in that the tray and the element both have a length to diameter ratio greater than 1.

39. In addition, it comprises a fin separated from the element from about 0.00254 to about 0.51 cm (0.001 to about 0.20 inches) and additionally comprising a separate fin lens from about 2.54 to about 15.24 cm ( 1 to approximately 6 inches) to which the cloud is directed.

40. The atomizer according to claim 39 or 9, characterized in that the objective is elongated and the element and the tray are angularly positioned to the objective.

41. The atomizer according to claim 39 or 9, characterized in that the fin is cylindrical in cross section.

42. The atomizer according to claim 39 or 9, characterized in that the fin has an aerodynamic surface thereon, this surface being flat.

43. The atomizer according to claim 39 or 9, characterized in that the objective is elongated, the element and the tray are parallel to the elongation of the objective, and the fin has edges that are spiral shaped to extend the full transverse width of the objective.

44. The atomizer according to claim 32, characterized in that the bristles are chosen from the group of bristles consisting of bristles of natural fiber, bristles of synthetic polymers and metal bristles.

45. The atomizer according to claim 32, characterized in that the transverse dimension of the bristles varies from twice the size of the particulate material to approximately 50 times the size of the particulate material.

46. The atomizer according to claim 32, characterized in that the bristles have a transverse dimension ranging from about 0.00254 to about 0.157 cm (0.001 inches to about 0.062 inches).

47. The atomizer according to claim 32, characterized in that the bristles have a length to transverse dimension ratio from about 10 to 1 to about 5,000 to 1.

48. The atomizer according to claim 32, characterized in that the bristles have a dimension in the direction of rotation ranging from about 0.00254 to about 0.157 cm (0.001 to about 0.062 inches).

49. The atomizer according to claim 31, characterized in that the bristles have a dimension transverse to the direction of rotation ranging from about 0.00254 to about 0.157 cm (0.001 to about 0.062 inches).

50. The atomizer according to claim 31, characterized in that the bristles have a ratio of bristle length to transverse dimension ranging from about 200 to 1 to about 800 to 1. SUMMARY OF THE INVENTION In the present invention there is disclosed an improved powder atomizer comprising a cylindrical tray, a resiliently deformable cylindrical member, which is hinged for rotation about an axis within the tray. The tray is mounted coaxially to the element. The element and the tray define a Venturi tube formed cylindrically between them in which the powder is fed. The Venturi tube has a radially separated inlet and outlet. A means is provided for rotating the element within the tray at speeds in excess of that required to eject the powder from the element by centrifugal force. The element draws ambient air through the Venturi tube and atomizes and de-agglomerates the dust fed into the venturi inlet, thereby forming a uniformly flowing cloud of particulate material that is uniform both longitudinally and laterally of this axis . The invention also provides a feeder and atomizer; and a deagglomerator combination of the feeder and atomizer combination with a feeder as described in U.S. Patent No. 5,314,090 which is particularly useful in wide-mesh coating applications to produce a cloud of particulate material that is uniform both laterally and longitudinally to the mesh and is uniform both in the distribution of the particulate material and in the particle size throughout the uniformly flowing cloud.