MXPA98009716A - Rotary atomizer with integrated shaping air - Google Patents

Abstract

A rotary atomizer has shaping members to generate shaping air without the need for independent sources of shaping air. The distribution and shape of the shaping members and the selection of rotating speed allows for the selection of virtually any pattern of distribution of atomized material. The shaping members are positioned to produce an outward flow of air from the rotary atomizer thereby eliminating the need for external sources of shaping air.

Description

ROTATING ATOMIZER WITH INTEGRATED CONFIGURATION AIR Background of the Invention 1 • Field of the Invention The invention relates generally to methods and apparatus for applying coatings. In particular, the invention relates to rotating atomizers that atomize material to be applied as a coating. In addition, in particular, the invention relates to a rotating atomizer that reduces or eliminates the need for air of external configuration to direct the atomized material towards an object to be coated. The coating material can be, for example, a liquid or a poivo. 2. Related Technique The use of rotary spray nozzles to apply coatings to an object is well known. One such application of rotary spray atomizers for coating objects is the application of a paint and other coatings to newly manufactured automobiles. Fig. 1 illustrates a conventional rotary atomizer, such as a cone cup 101 attached to the turbine 103.

Rotary atomizers typically have a uniform outer surface. Typically, an arrow in the turbine (not shown) causes the cone cup to rotate at a desired speed. The material to be atomized, such as paint, is supplied to the cone cup as it rotates. The paint or other material to be sprayed travels along the inside of the cone cup and exits the cone cup 101 through a single opening or a plurality of openings 105 in the face of the cone cup . In order to control the shape of the distribution of the atomized material, the configurator air is transmitted through the outlets 107 of the turbine 103. The configurator air is typically supplied from an independent source to achieve the configured fan pattern of the distribution of the atomized product shown generally at 109 in Fig. 1. Essentially, the configurator air directs matter! atomized outwards and away from the cone cup 101 to avoid too wide distribution of the material as shown by dotted line 111. One feature of this type of rotary atomizer is the presence of a "cake" of atomized material 113. The cake of atomized material creates imperfections in the application of the atomized material as a coating, such as in paint applications. Regardless of the use of independent configurator air to direct atomized materials such as paint away from cone cup 101, the "air return" of such material is always a problem. Different devices such as a configurator air plate or a configurator air corona have been used to reduce the return of air. However, when the external configurator air is used, part of the atomized coating material inevitably moves behind the rotary atomizer or the cone cup thereby coating the rotary atomizer, the turbine housing and any other components attached thereto. The return of air from the coating material onto the cone cup of the cone atomizer, the turbine housing and other components results in increased maintenance, since such components require constant cleaning. In addition, the return of air from the coating material to the turbine decreases the life expectancy of the turbine and reduces the coating efficiency and performance.

Brief Description and Objects of the Invention It is an object of the invention to provide a rotary atomizer that significantly reduces or eliminates the shortcomings of conventional rotary atomizers by using an independent source of configurator air. Another object of the invention is to provide a rotating atomizer that generates its own configurator air without the need for an independent source of configurator air. The above and other objects of the invention are achieved by a rotary atomizer which includes a rotating member having an inlet side for receiving material for atomization and an outlet side for discharging the atomized material. The atomizer also includes a plurality of configurator members on an outer portion thereof. The shaping members may be channels on an outer surface of the rotating member or vanes, fins or other pallets. As the rotating member rotates, configurator air is required to overcome centrifugal forces in the coating material that leaves the outer edges of the bell cup produced by the air passing through the channels or blades. This self-generated configurator air drives the atomized material, such as a coating material, in the desired direction. For example, atomized paint is directed towards the surface of the object to be coated using configurator air generated by the rotating atomizer without the need for an independent source of configurator air.

Brief Description of the Drawings The above and other objects of the invention are achieved by a rotary atomizer as described herein in conjunction with the drawings in which: Fig. 1 illustrates a distribution pattern of atomized material using a conventional atomizer. Fig. 2 shows an embodiment of a rotary atomizer according to the invention attached to a turbine. Figs. 3a and 3b are front and sectional views respectively of the rotary atomizer and the turbine shown in Fig. 2. Fig. 4 is a cross section of a rotary atomizer according to the invention. Fig. 5 is a side view of a rotary atomizer according to the invention. Fig. 6 is a rear view of a rotary atomizer according to the invention. Fig. 7 is a perspective view of a rotary atomizer according to the invention. Fig. 8 is a cross section of a rotary atomizer along line B-B in Figs. 5 and 7. Fig. 9 illustrates an alternative embodiment according to the invention. Fig. 10 illustrates another alternative embodiment according to the invention. Fig. 11 illustrates another embodiment according to the invention.

Detailed Description of the Preferred Modalities In Fig. 2, one embodiment of a rotary atomizer and turbine assembly is shown generally at 201. A rotating member 203 is attached to the turbine assembly 205. As shown in Fig. 2, the rotating member 203 is a cone shaped like a bell. The bell-shaped cone 203 in Fig. 2 is by way of example and not limitation, since any form of rotary member may be used in accordance with the invention. Conventional rotary atomizers have a uniform outer surface. A distinctive feature of the rotary atomizer 203 according to the invention is the existence of one or more shaping members 207 on an outer surface of the rotating member 203. As further illustrated herein, the shaping members 207 are channels or indentations formed in the outer surface of the bell like of the rotating atomizer. The use of the indentations on the outer surface of the bell cone of the rotary atomizer to form the shaping channels is by way of example and not limitation. For example, in another embodiment the forming members may be formed using raised members such as vanes, vanes or vanes extending outward from the outer surface of the bell cone of the rotating atomizer. For purposes of illustration herein, the invention will be further explained using channels as an illustration, although it will be understood that the forming members may be formed using the same principles used by vanes, vanes or vanes. Figs. 3a and 3b show a front view and a cross section respectively of the assembly shown in Fig. 2. The bell cone of the rotary atomizer 203 having channels 207 rotates with the rotation of an arrow member 301 driven by a motor (not shown). ) in the turbine engine housing 303. An injection manifold, such as a paint injection manifold 305, is connected to an inlet 307 for a supply of material, such as paint, to be atomized. The paint provided to the injection manifold 307 is directed towards an inlet portion 309 of the bell cone of the rotary atomizer 203. The paint or other material to be atomized is moved through the inlet section, is atomized in the bell cone of the rotary atomizer 203 as the atomized material through the outlets 311. Typically the outlets 311 are a series of holes in an outlet side of the rotary atomizer or bell cup. An important feature of the invention is the elimination or reduction of the need for an independent source of configurator air. As a result of the presence of the configurator members 207, such channels or vanes on the outer surface of the rotary atomizer, such as the bell cone 203, the rotary atomizer generates its own configurator air. The exact distribution pattern of the atomized material depends, for example, on the geometry of the shaping members 207, the number and location of the shaping members and the rotation speed. The experimental results suggest that the distribution pattern of the atomized material narrows as the volume of the configurator air increases. Figs. 2 and 3b show that as the rotary atomizer such as the bell cone 203 rotates, the ambient air passes along the outer surface and enters the channels 207 from a rear portion 313 of the rear channel to the rear portion 315 of the member rotary 203. The ambient air exits the channel 207 in the front portion 317 which is on a front edge 319 of the rotary atomizer 203. The self-generated configurator air exiting the front portion 317 of the channels 207 directs the distribution of the material atomized. Fig. 4 is a sectional view of the rotating member 203 and illustrates a possible geometry of the shaping members 207. As shown in Fig. 4, the shaping member 207 is a channel cut on the outer surface of the rotating atomizer 203 With a substantially uniform curve the channel has a generally U-shaped shape. However, the channels can also be formed with edges that form squares or rectangles or in a V-shape. Other more complicated channel shapes are also within the reach of the channel. invention. The F? G. 5 is a side exterior view of the bell cone of the rotary atomizer 203 illustrating one embodiment of the invention in which the shaping members 207 are placed one behind the other on the outside of the rotating atomizer 203. The shaping members 207 can be placed directly one immediately following the other as shown in Fig. 5 or they may be separated from one another to create different distribution patterns of the atomized material. The angle at which the configuration member is placed on the outer surface of the rotating atomizer can also affect the distribution pattern of the atomized material. As noted previously, the effect of the configurator members is to generate the configurator air from the ambient air. The ambient air is directed out from the edge 319 of the rotary atomizer 203 in a similar fan pattern. As noted previously, the experimental results suggest that the shape of the pattern is a function of the volume of air moved, with a narrower pattern that results in increasing the amount of air moved. Therefore, for a particular set of forming members in a rotary atomizer, the fan pattern or distribution of atomized material would be expected to be narrow as the rotation speed increases. The fan pattern can also be affected by the geometry of the configurator air members, either channels or blades. An inclination angle can be defined as an angle measured from the center line 501 of the channel 207 to the center line 503 of the rotary atomizer 203. A positive inclination angle can be defined in which the rear portion 313 of the channel 207 is offset from the front portion 317 of channel 207 in a direction to cause a flow of configurator air outwardly from front edge 319 of rotating member 203. Therefore, in the case where rotating member 203 rotates in a left-handed direction as seen from the front, a positive inclination angle has the rear portion 313 of the shaping member offset to the left of the front portion 317 of the shaping member, thereby creating an outward air flow to generate a fan to control the distribution of the material atomized. A negative tilt angle has the opposite effect, so it tends to invert the flow of the configurator air towards the rotating member. When the rotating member rotates in a counter-clockwise direction, a negative inclination angle has the rear portion 313 of the configurator member to the right of the front portion 317 of the configurator member as seen from the front of the rotating member 203. When the rotation of the member Rotary is in a clockwise direction, the positive and negative tilt angles are reversed. In addition to the separation of the shaping members 207, the number of the spacing members may also be selected to achieve the desired pattern of distribution of the atomized material. Therefore, the shape of the distribution is affected by the number of shaping members 207 on the outside of the rotating atomizer 203, the relative spacing of the shaping members 207, the depth 207, the depth of the shaping member 207, the width of the member configurator 207 (the width of the top of the channel and at its bottom may be different), the inner shape of the shaping member 207 and the relative tilt angle as measured from a central axis from the front edge of the rotary atomizer. In addition, the length of the shaping member from the front of the shaping member 317 towards the rear of the shaping member 313 may also be selected to influence the distribution pattern of the atomized material. Fig. 6 is a rear view of the bell cone of the rotary atomizer 203 showing the relative position of the shaping members 207. Fig. 7 is a rear perspective view of the bell cone of the rotary atomizer 203 and fig. 8 is a view along section B-B of Figs. 5 and 7. Fig. 8 illustrates that the depth of the shaping member 207 can be selected. Another parameter of the shaping member that can be selected is its tilt, defined as a change in the depth of the shaping member. For example, the shaping member 207 may be deeper at an edge 317 where the shaping air comes out and less deep at the edge 313 where the shaping air enters. The opposite inclination can also be used and the inclination could vary along the length of the shaping member to achieve a desired configurator air pattern. As previously identified, the shaping members may be indentations or channels as shown in those drawings or may be raised vanes, or vanes or vanes on the outer surface of the rotary atomizer 203. The invention applies to any rotating element such as the cone bell shaped shown herein or a flat side cone or plate or arrow or any other type of rotary atomizer or device. The blades or fins can be used in place of the indented channels as shown here. A rotary atomizer according to the invention can be used to distribute any type of material to be atomized, such as a powder or a liquid paint or solvent. A typical application would include the application of spray paint or other coatings. As previously described, for a particular configuration of a rotary atomizer having such configurator members, the distribution of the atomized material seems to vary with the speed of the turbine. Therefore, different fan patterns can be achieved using different rotation speeds. For example, when a primer coating requires a distribution pattern and a finish coating requires a different distribution pattern, different patterns can be obtained with the same rotating member by changing the rotation speed. When the speed of the turbine is controlled by other considerations, the rotating member can be formed with shaping members which produce the desired pattern at the desired rotation speed. As previously indicated, the desired pattern is influenced by the selection of the inclination, slope, depth, length, width, shape and number of forming members and their relative positions on the outside of the rotating member. An atomizer with shaping members as described herein may be substituted in any application where the independent shaping air is used. As previously described herein, conventional rotary atomizers tend to develop the "cake" effect illustrated in FIG. 1 of the present. The coating particles that fall from the cake tend to introduce imperfections in the finished coatings. As the coating material leaves the rotary atomizer such as the bell cone, the larger particles tend to separate from the smaller particles. In order to achieve a uniform coating these larger and smaller particles need to be mixed thoroughly. The atomizer according to the invention generates sufficient air moving forward to keep the coating material moving towards the object to be coated. This also tends to create the "spiral effect" inside the configurator air cone / coating material. The spiral effect created by the vanes or channels helps to mix the particles of different sizes that produce a more uniform coating finish. Electrostatic techniques have been used to apply coatings such as paint on large flat surfaces. In electrostatic painting techniques, the paint and the object to be coated are loaded in an opposite manner in order to cause the paint to be attracted to the object. One reason for the introduction of electrostatic painting techniques is the existence of the cake of the coating material produced by the atomizer and the need to attract the coating material out of the cake. The self-generated forward moving air produced by the shaping members on the outside of the rotating member according to the invention significantly reduces or eliminates the cake, thereby improving the efficiency of the paint transfer and reducing the amount of products. volatile organic chemicals present. The reduction in volatile organic chemicals reduces risks and improves safety. The reduction or elimination of the cake can also improve the performance of the coating in paint spray booths employing vacuum cleaners. In some manufacturing facilities, a large surface to be sprayed with a coating is placed inside a spray booth and a vacuum cleaner in the booth is used to extract excess spray from the cake to the object that is going to paint. The reduction or elimination of the cake in the present invention reduces the excess of spraying, thus improving the efficiency of the paint transfer in the vacuum cleaner and making it easier to control. As a result, the invention reduces coating imperfections and produces a more uniform finish. In applications where electrostatic is employed, the larger surface area resulting from the forming members allows the rotating member to accumulate more load thereby improving the efficiency of the transfer, in essence, the increased surface area of the rotating member seems larger, thus accumulating more load on its surface. It should be noted that in electrostatic painting applications, the top edge is preferably not sharpened so as to reduce the possibility of the crown which would lead to undesirable bowing. In addition, it is recommended that the configurator members have no sharp edges so that they can be handled more conveniently by personnel without the risk of injury. The self-generation of a sufficient volume of air by the shaping members to direct the distribution of the material outward and away from the rotating member reduces the amount of air return when compared to conventional systems using independent sources of configurator air. Reduced air returns reduce the amount of paint that builds up on the turbine and increase the life of the turbine. This effect also reduces the need for complicated "air seals" to protect the turbine from damage by the return of air from the material to it. The self-generation of the configurator air achieved according to the invention reduces the need for compressed air, whose conventional systems are used to provide configurator air. This reduction in the need for compressed air improves energy efficiency and reduces cost.

Figs. 9 and 10 illustrate two alternative configurations of configurator members in a rotating member. In Fig. 9, the rotating member 901 has the shaping members 903. As the member 901 rotates, ambient air enters the shaping members 903 in the rear portion 905. The rear portion 905 is at an angle of approximately 90 ° toward the face 907 of the rotating member. This allows the maximum amount of air to enter the configurator member. The air moves through the configurator member and exits at the front portion 909. The front portion 909 is shown having an outlet angle that affects the distribution pattern of the atomized material. The distribution pattern seems wider as the angle increases. The shaping members 903 have a smooth transition between the inlet 905 and the outlet 909. Fig. 10 shows a rotating member 1001 with shaping members 1003. The air enters the shaping members 1003 at the inlet 1005 and exits at 1007. The members Configurators 1003 are characterized by an acute transition 1009. The sharp transition allows reversal of the direction of rotation and creates the drag that slows down the configurator air. Other patterns that include zigzag patterns of configurator members can be formed in the rotating member in order to achieve the desired effects. Fig. 11 illustrates another configuration according to the invention. In Fig. 11 the vanes or vanes 1101 are located relative to a conventional rotary atomizer, so that the configurator air flow is generated when the rotary atomizer is rotated. In the example shown in fig. 11, the vanes 1101 are positioned behind a conventional atomizer, such as the bell cone 1103. The vanes 1101 can rotate independently of the atomizer 1103 or can rotate synchronously with the atomizer 1103. The vanes 1101 can also remain stationary as they rotate the atomizer. The vanes 1101 are configured to direct air outwardly from the atomizer 1103 as the atomizer rotates. Further, in any rotary atomizer combinations of positive and negative inclination shaping members may be used and the parameters previously described herein may be varied to achieve the desired distribution of atomized material. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention described herein. It is intended that the specification be considered only as an example, with the actual scope and spirit of the invention which is indicated by the following claims.

Claims (20)

1. A rotary atomizer comprising: a rotating member having an inlet side for receiving material for atomization and an outlet side for discharging the atomized material; a plurality of shaping members on an outer portion of said rotating member.

2. A rotary atomizer as recited in claim 1, the forming members comprising channels on an outer surface of the rotating member.

3. A rotary atomizer as recited in claim 2, the channels extending from a front edge of said rotary member to a rear part of said rotary member.

4. A rotary atomizer as recited in claim 3, a rear portion of at least one of the channels that is offset from a front portion thereof, said front portion that is located at said front edge of the rotating member.

5. A rotary atomizer as recited in claim 4, the rear portion that is offset from the front portion in a direction that produces a flow of configurator air out from a face of said rotary member.

6. A rotary atomizer as recited in claim 4, the front portion that is positioned at an entry angle and the rear portion that is positioned at an exit angle different from the entry angle.

7. A rotary atomizer as recited in claim 6, the entry angle and at least one of the channels having a positive inclination.

8. A rotary atomizer as recited in claim 2, the rotating member comprising a bell cone.

9. A rotary atomizer as recited in claim 2, the rotating member comprising a rotating shaft. A rotary atomizer as cited in claim 2, the channels having at least one of a depth, width, shape and inclination selected to produce a desired distribution of said atomized material. 11. A rotary atomizer as recited in claim 10, each of the shaping channels having substantially the same depth, width and inclination. 12. A rotary atomizer as cited in claim 10, in at least one of the channels having a different value from at least one of said depth, width and inclination of the others of said channels. 13. A rotary atomizer as recited in claim 1, the rotary atomizer distributing the atomized material differently at different rotational speeds of said rotating member. 14. A rotary atomizer as cited in claim 1, the forming members comprising blades. 15. A rotary atomizer as cited in claim 14, the blades having a shapes and a position to produce a desired distribution of said atomized material. 16. A method of atomizing a material, the method comprising the steps of: applying the material to be atomized to an inlet portion of a rotating member having forming members in an outer portion thereof; rotating the rotating member at a speed to distribute the atomized material emitted from an outlet portion of said rotating member in a desired pattern. 17. A method of coating an article with a material, the method comprising the steps of: atomizing the material into a rotating member having shaping members on an outer portion thereof, the shaping members that produce desired patterns of atomized material at selected rotation speeds; and apply the atomized material to said article. 18. A rotary atomizing system comprising: a rotary atomizer; a plurality of vanes positioned relative to said atomizer to generate a configurator air flow when the rotary atomizer rotates. 19. A system as recited in claim 18, wherein the vanes rotate independently of said rotation of said rotary atomizer. 20. A system as recited in claim 18, wherein the vanes rotate synchronously with said rotary atomizer.