WO2008084095A2

WO2008084095A2 - Coating of articles with optional pulsing and recycle of coating material

Info

Publication number: WO2008084095A2
Application number: PCT/EP2008/050289
Authority: WO
Inventors: Angelo Bellini; Ralf Scheuffgen; Claus Ruschitzka; Walter Jahn
Original assignee: Nordson Corporation
Priority date: 2007-01-11
Filing date: 2008-01-11
Publication date: 2008-07-17
Also published as: WO2008084095A3

Abstract

A powder coating apparatus capable of applying powder coating material into articles at high production rates while recovering oversprayed powder is provided. The apparatus may include a powder coating applicator that may form part of a circulation loop for powder coating material from a supply, through the applicator, and back to the supply. The powder coating apparatus may rapidly switch between applying powder coating material and circulating the powder coating back to the supply. In one embodiment, the applicator includes an inlet and a diverter having a first operating mode during which powder coating material flows from the inlet to a first coating material outlet for a coating operation, and a second operating mode during which powder coating material flows from the inlet to a second coating material outlet for a non-coating operation. The coating applicator may be reciprocated into and out of a container such as a tube, with powder sprayed by the applicator into the tube as the applicator is lanced into the tube, and with oversprayed powder which does not adhere to the interior of the tube being pulled back through the applicator as the applicator is withdrawn back out of the tube, for example. A densifier, or condensing device, may be used to remove air from the air entrained powder, and increase the powder to air ratio before the powder is sprayed from the applicator into the container.

Description

COATING OF ARTICLES WITH OPTIONAL PULSING AND RECYCLE OF COATING MATERIAL

Related Applications

[0001] This application claims priority to, and any benefit of, U.S. Provisional

Patent Application Ser. No. 60/884,488, filed January 1 1, 2007 for INSIDE POWDER COATING OF TUBES AND AEROSOL CANS, the entire disclosure of which is fully incorporated herein by reference.

Background

[0002] During the production of metal cans, such as aerosol cans, for example, a coating is typically applied to the interior surface of the cans. Powder coatings are often used because they are solvent free, thus avoiding solvent emissions. US Patent 5,725,670, which is incorporated herein by reference in its entirety, shows an apparatus for powder coating the interior of metal cans. US Patent 5,474,609, which is also incorporated herein by reference in its entirety, shows an apparatus for coating the score lines of easy open can ends in a repair coating operation.

[0003] Applying powder coating to small diameter tubes and aerosol cans is challenging because these tubes and cans must be coated at high production rates and any oversprayed powder coating material that does not adhere to the inside of these articles must be removed. Prior art systems have not adequately addressed these challenges.

Summary

[0004] The inventions relate generally to an apparatus and method for applying a powder coating material to an article, such as for example, but not by way of limitation, the interior of tubes and aerosol cans. In one embodiment, an apparatus may include a supply of powder coating material, a pump for pumping powder coating material from the supply, and a powder coating applicator that receives powder coating material from the pump and is used to coat an article with the powder coating material. [0005] In accordance with an inventive aspect of the disclosure, a powder coating apparatus and method is provided capable of directing pulses of powder coating material toward articles. In one embodiment, the apparatus is adapted to rapidly switch between spraying powder coating material toward articles during a coating operation and drawing both powder coating material from the powder outlet of the apparatus and powder overspray through a recycle outlet and back to a powder supply. [0006] In one embodiment, the articles are mounted on a device that moves the articles past a powder coating applicator. The powder coating applicator may be mounted on a device that reciprocates the spray outlet of the powder coating applicator into and out of the articles.

[0007] In another embodiment, a powder coating apparatus has a first operating mode during which powder coating material flows to a first coating material outlet for a coating operation, and a second operating mode during which powder coating material is diverted to flow to a second coating material outlet for a non-coating operation. Cycling the powder coating apparatus between the first operating mode and the second operating mode may produce a pulsed flow of powder exiting the powder coating apparatus. In another embodiment, in the non-coating operation, powder coating material is recycled back to a powder coating material supply.

[0008] In accordance with another inventive aspect of the disclosure, a powder coating apparatus is provided that continuously flows powder coating material through a powder coating applicator. In one embodiment, the applicator has a first operating mode in which powder coating material is directed toward an article to be coated and a second operating mode in which the applicator forms part of a circulation loop for powder coating material from a supply, through the applicator, and back to the supply. In one embodiment, the apparatus switches from the first operating mode to the second operating mode when a pump is turned on.

[0009] In another embodiment, a powder coating applicator may include an optional powder concentrating device to increase the powder to air ratio exiting the applicator. The powder concentrating device may include an inlet that receives powder coating material from a supply and the outlet that has a smaller diameter than the inlet. In one embodiment, the powder concentrating device may include a conical flow path between the device inlet and the device outlet and a powder condenser outlet that allows air to be removed from the powder-air mixture supplied to the powder concentrating device.

[0010] Further advantages and benefits will become apparent to those skilled in the art after considering the following description and appended claims in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0011] In the accompanying drawing, which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify embodiments of the invention.

[0012] Figure 1 is schematic of an embodiment of a powder coating apparatus for coating an article;

[0013] Figure 2A is a side view of an embodiment of a powder coating applicator of the apparatus of Figure 1;

[0014] Figure 2B is a cross section of the extension and powder concentrating device of the powder coating applicator of Figure 2 A; and

[0015] Figure 3 is a side view of a second embodiment of a powder coating apparatus for coating an article.

Detailed Description

[0016] While the exemplary embodiments described herein are presented in the context of a powder coating apparatus including an electrostatic powder coating applicator for coating the interior of a tubular article, those skilled in the art will readily appreciate that the present invention may be configured and applied in a variety of ways. For example, , the apparatus may be used to apply a coating material to articles or other than tubular objects and surfaces other than interior surfaces. Furthermore, the applicator may be configured to electrostatically charge the coating material or may be configured as a non-electrostatic applicator. Still further, the applicator may be operated manually or may be configured to operate automatically. These examples and the disclosed exemplary embodiments are intended to illustrate the broad application of the invention and provide no limitation on the present invention.

[0017] While various inventive aspects, concepts and features of the inventions may be described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects, concepts and features may be used in many alternative embodiments, either individually or in various combinations and sub- combinations thereof. Unless expressly excluded herein all such combinations and sub- combinations are intended to be within the scope of the present inventions. Still further, while various alternative embodiments as to the various aspects, concepts and features of the inventions— such as alternative materials, structures, configurations, methods, circuits, devices and components, software, hardware, control logic, alternatives as to form, fit and function, and so on—may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or later developed. Those skilled in the art may readily adopt one or more of the inventive aspects, concepts or features into additional embodiments and uses within the scope of the present inventions even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the inventions may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present disclosure; however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated. Moreover, while various aspects, features and concepts may be expressly identified herein as being inventive or forming part of an invention, such identification is not intended to be exclusive, but rather there may be inventive aspects, concepts and features that are fully described herein without being expressly identified as such or as part of a specific invention, the inventions instead being set forth in the appended claims. Descriptions of exemplary methods or processes are not limited to inclusion of all steps as being required in all cases, nor is the order that the steps are presented to be construed as required or necessary unless expressly so stated. [0018] Figure 1 illustrates an exemplary embodiment of an apparatus 5 that may be used for practicing the inventions. The apparatus 5, however, may be configured in a variety of ways and the apparatus of Figure 1 is merely an example of one possible apparatus for practicing the inventions. A first, and optionally, fluidized powder coating material hopper 10 may contain virgin or reclaimed powder coating material. A pump 12 fluidly communicates with the first powder hopper 10 to draw powder coating material from the hopper and supply the powder to a first cyclone separator 14 via a fluid conduit 16 or other suitable means. Powder material delivered to the cyclone 14 is separated and falls to through a sieve 18 and into a main powder hopper 20, which is also a fluidized hopper. A pump 22, such as a venturi pump, for example, is mounted on main hopper 20 to draw powder from the hopper and supply the powder coating material to a feed hopper 24 via a fluid conduit 25 or other suitable means. The feed hopper 24 may also be a fluidized hopper.

[0019] A level sensor (not shown) is provided on the feed hopper 24 to maintain a constant level of powder in the feed hopper. A pump 26, such as a venturi pump for example, is associated with the feed hopper 24 to draw powder coating material from the feed hopper and supply the powder coating material to one or more powder coating applicator(s) 28, such as an electrostatic powder spray gun, via one or more fluid conduits 30. In the embodiment of Figure 1, two powder coating applicators 28 are illustrated as operating in series to coat two articles simultaneously. The apparatus 5, however, may be configured with more or less than two powder coating applicators and may coat more or less than two articles simultaneously.

[0020] The powder coating applicator(s) 28 are arranged to spray powder coating material onto one or more articles 32. In one embodiment, the articles are tubular objects or metal cans. The article(s) 32 may be mounted on a device 34 that moves the article(s) past the powder coating applicator 28. For example, the articles 32 may be mounted by a vacuum chuck on a star wheel that rotates them past the powder application device 28. The powder coating applicator 28 may also be mounted on a device 36, such as a reciprocator or gun mover, that moves the spray end of the powder coating applicator 28 relative to the work piece. For example, the device 36 may move the spray end of the applicator 28 into and out of the interior of the article 32, into and out of a spray booth, towards and away from the article, up and down relative to the article, or other suitable movement relative to the article. The article 32 may optionally be electrically grounded to the device 34 so that electrostatically charged powder sprayed from the powder coating applicator adheres to the article.

[0021] The apparatus 5 may also include a powder recovery apparatus to capture any oversprayed powder that does not adhere to the article 32. An enclosure 38, such as a spray booth, for example, may be provided around the articles 32 to contain oversprayed powder. A vacuum source 40, such as a fan, may be used to drawn air- entrained powder from the enclosure and convey the air-entrained powder through an after- filter 42 to separate the powder from the air.

[0022] Referring to Figures 2A and 2B, a first embodiment of a powder coating applicator 28 is illustrated. The powder coating applicator 28 may be configured in a variety of ways. Any powder coating applicator, such as a spray gun, that can form part of a circulation loop for continuously circulating powder coating material and/or is capable of spraying pulses of powder coating material into articles may be used. In the illustrated embodiment, the powder coating applicator 28 is an electrostatic spray gun that applies an electrostatic charge to the powder coating material so that it is attracted to a grounded article.

[0023] The powder coating applicator 28 includes a body portion 50 defining an inlet 52 (Figure 2A) and an outlet 54 (Figure 2B), a powder concentrating device 56, such as, for example, a densifier, and an extension 58. The powder coating applicator 28 may be configured to include the body portion 50, the powder concentrating device 56, and the extension 58 in a single integrated design. The powder coating applicator 28, however, may also be a known or newly developed powder coating applicator that is modified such that a powder concentrating device and an extension are added onto the applicator. For example, a Sure Coat® automatic spray gun, available from Nordson Corporation of Amherst, Ohio, USA has been found suitable to be modified to include a powder concentrating device and extension. This gun is shown in US Patent Number 6,478,242, which is incorporated herein by reference in its entirety. [0024] The powder concentrating device 56 is positioned between the body portion 50 and the extension 58. The powder concentrating device 56 may be configured in a variety of ways. Any structure that increases the powder to air ratio of the air- entrained powder may be used. For example, a powder concentrating device design for condensing a powder-air mixture is shown as element 70 of Figure 5 in US Patent 5,725,670 reference above.

[0025] In the depicted embodiment, the powder concentrating device 56 includes an inlet 60, positioned to receive air-entrained powder from the body outlet 54, and an outlet 62 connected to the inlet by a powder flow passage 64 extending longitudinally therethrough. The diameter of the powder flow passage 64 reduces between the body outlet 54 and the extension 58. In the depicted embodiment the flow passage 64 is generally conical, though other shapes are also possible.

[0026] The powder concentrating device 56 also includes a powder condenser outlet 66 positioned between the powder concentrating device inlet 60 and the powder concentrating device outlet 62.

[0027] In operation, as the flow of air-entrained powder moves through the powder concentrating device 56, the portion of air-entrained powder towards the center of the flow passage moves faster than the air-entrained powder closer to an interior wall 68 because of the friction created by the movement of the air-entrained powder against the interior wall surface. While both air and powder are vented out of the powder condenser outlet 66, more air than powder is naturally drawn off through the outlet. This occurs because the mass of the powder, having a greater momentum than that of the air, naturally continues to move downstream past the powder condenser outlet 66. However, when the air encounters the constricting diameter of the interior wall 68 of the powder concentrating device 56, it naturally seeks the easiest flow path, i.e. through the powder condenser outlet 66. Of course, some powder is still mixed with the air that vents through the outlet 66, but the powder concentration relative to the air vented through the powder condenser outlet 66 is relatively low. On the other hand, the powder concentration relative to the air that exits the powder concentrating device outlet 62 is relatively high.

[0028] Thus, the amount of powder that the applicator can be delivered to coat an article can be increased without increasing the volume of air in which the delivered powder coating material is entrained. In an application, such as for example, coating the interior surface of a container body, the higher powder- to-air ratio delivered allows for effective coating of the entire interior surface of the container bodies moving at high speeds without needing to remove a high volume of transport air from within the container bodies.

[0029] The powder condenser outlet 66 is connected to a cyclone separator 44 by a conduit 46 or other suitable means. The air-powder mixture that exits the powder condenser outlet 66 enters the cyclone separator 44, which separates the powder from the air and deposits the powder into the feed hopper 24.

[0030] The densified, or condensed, powder stream exits the powder concentrating device 56 and enters into an extension 58. The extension 58 may be configured in a variety of ways. Any structure that allows, in one operating mode, a powder coating material to be directed to an article in a coating operation while also allowing, in a second operating mode, for the powder coating material to be diverted back through the extension may be used.

[0031] In the depicted embodiment, the extension 58 has a generally elongated configuration that includes a first or inner conduit 70 and a second or outer conduit 72. The inner conduit 70 is concentrically disposed within the outer conduit 72 such that an annular flow passage 74 is formed between the two conduits. The flow passage 74, however, may be configured other than annular.

[0032] The inner conduit 70 has a first end 76 defining an inlet 78 that receives the concentrated powder stream from the powder concentrating device outlet 62 and a second end 80 defining an outlet 82. The outer conduit 72 has a first end 84 connected to a powder recycle outlet 86 and a second end 88 that extends beyond the outlet 82 of the inner conduit 70 and is open-ended to define an outlet 89. Thus, the outlet 82 of the inner conduit 70 is recessed within the outer conduit 72. A pump 48, such as a venturi pump, is connected to the powder recycle outlet 86 by a conduit 49 or other suitable means. [0033] In operation, the powder application apparatus 5 can operate in a first operating mode of operation wherein the powder coating applicator directs powder coating material out of the outlet 89 of the outer conduit 72 to coat an article and a second operating mode in which the powder coating applicator 28 forms part of a circulation loop for powder coating material. In both the first operating mode and the second operating mode, powder coating material is flowing through the powder coating applicator 28 and out of the outlet 82 of the inner conduit 70.

[0034] In both the first operating mode and the second operating mode, the pump

26 delivers powder from the feed hopper 24 to the powder coating applicator(s) 28. The applicator body 50 applies an electrostatic charge to the powder coating material and the powder concentrating device 56 increases the density of the powder-air mixture as described above. Applicator 28 applies an electrostatic charge to the powder in a well- known manner. An electrical cable 92 is connected to the back of the gun to supply the necessary electrical current and voltage from an power source 94. A voltage multiplier (not shown) is contained within applicator 28 to step up the voltage to a high voltage within the gun. This voltage is applied to an electrode (not shown) that is positioned within the powder flow stream to apply an electrostatic charge to the powder. US Patent 6,478,242, which is incorporated herein by reference in its entirety, shows an example of this type of prior art gun. The electrically charged and concentrated powder-air mixture travels through the flow path 78 of the inner conduit 70 and exits the inner conduit outlet 82.

[0035] In the second operating mode, the pump 48 is turned on. Thus, the powder coating material that exits the inner conduit outlet 82 is immediately drawn back through the passage 74 in the extension 58 and out of the condenser recycle outlet 86 by the pump 48. The air-entrained powder drawn by the pump 48 is conveyed to the cyclone 14 via a conduit 90 or other suitable means and deposited back in the main hopper 20.

[0036] In the first operating mode, the pump 48 is momentarily turned off. As a result, the powder coating material exiting the outlet 82 of the inner conduit 70 is no longer diverted back through the passage 74 and, thus, exits the extension 58 to coat the desired surface of the article.

[0037] As indicated above, the powder coating applicator 28 may be used to coat the interior surface of a can or tube and may be mounted on a reciprocator that lances the extension into and out of the can or tube. In this application, as the applicator 28 is being lanced into the can or tube, the pump 48 is turned off to allow powder to be sprayed from the applicator into the can or tube. As the applicator 28 is being withdrawn from the can or tube, the pump 48 is again turned on to withdraw from the interior of the can or tube any oversprayed powder that does not adhere to the interior of the article. This oversprayed powder is drawn back into the annular passage 74 and powder recycle outlet 86 along with the powder-air mixture exiting the inner conduit outlet 82. [0038] Thus, the apparatus 5 may continuously circulate powder coating material in a loop from the powder supply 24, through the applicator 28, and from the inner conduit outlet 82 back to the supply. Since the powder coating material is continuously circulating through the powder coating applicator 28 when it is not being sprayed, it can be pulsed at high frequency from the gun using the method described above as necessary to coat articles at a high production rate while providing an effective way to collect overspray that does not coat on the surface of the articles. [0039] Referring to Figure 3, a second embodiment of a powder coating applicator 128 is illustrated. The powder coating applicator 128 may be configured in a variety of ways. Any powder coating applicator, such as, for example, a spray gun, that can form part of a circulation loop for powder coating material and/or is capable of spraying pulses of powder coating material into articles may be used. [0040] In the depicted embodiment, the powder coating applicator 128 includes a body portion 150, a diverter 154, and a control 156. The powder coating applicator 128 may be configured to include the body portion 150 and the diverter 154 as a single integrated design. The powder coating applicator 128, however, may also be a known or newly developed powder coating applicator that is modified such that the diverter 154 is added onto the applicator.

[0041] The body portion 150 defines a powder inlet 152 and includes a mounting or gripping portion 160 that allows the applicator 128 to be mounted onto a device for moving the applicator, such as for example, a reciprocator, or to be gripped by a user. Thus, the applicator 128 may be configured for manual use or for automatic use. The diverter 154 and the control 156 cooperate to allow the powder coating applicator to operate in two modes. In a first operating mode, powder coating material that enters the powder inlet 152, flows from the inlet to a first coating material outlet 162 for a coating operation, such as directing the air-entrained powder toward an article to be coated. In a second operating mode, the powder coating material flows from the powder inlet 152 to a second coating material outlet 164 for a non-coating operation, such as for example, to be directed back to a powder supply source. Thus, in the second operating mode, the powder coating applicator 128 forms part of a circulation loop from a powder supply source, through the applicator, and back to the powder supply source. [0042] The diverter 154 may be configured in a variety of ways. Any structure capable of delivering powder coating material to a first coating material outlet for a coating operation in a first operating mode and diverting the powder coating material to a second coating material outlet 164 for a non-coating operation in a second operating mode may be used.

[0043] The control 156 cooperates with the diverter 154 to change the operating mode of the powder coating applicator 128. The control 156 may be configured in a variety of ways. For example, in one embodiment, the control 156 includes a pump in fluid communication with the second coating material outlet 164 and a pump controller. When the pump is off, the powder entrained air is directed from the first coating material outlet 162 toward an article to be coated. When the pump is turned on, it diverts the powder entrained air away from the first coating material outlet 162 by drawing the powder entrained air through the second coating material outlet 164. In addition, some overspray powder material that did not adhere to the article to be coated may also be drawn through the second coating material outlet 164 by the pump. In both the first operating mode and the second operating mode, powder coating material continuously flows through the powder coating applicator 128.

[0044] In the exemplary embodiment of Figure 3, the diverter 154 may be positioned at the end of the powder coating applicator 128. As a result, powder coating material is continuously delivered up to the end of the applicator 128, even during a non- coating operation (second operating mode). As a result, when the powder coating applicator 128 changes to a coating operation (first operating mode), powder coating material has already been delivered to the end of the powder coating applicator 128 and can be immediately directed toward the article to be coated. In this manner, by switching between the first operating mode and the second operating mode, powder coating material can be pulsed at high frequency from the powder coating applicator 128 to coat articles. [0045] The apparatus, therefore, provides a means for applying powder coating to the articles, such as, for example, the interior of small diameter cans and tubes, while effectively collecting any overspray powder that does not adhere thereto. Moreover, the apparatus can be used at a high production rate with the ability to deliver high frequency pulses of powder coating material.

[0046] The inventions have been described with reference to exemplary embodiments. Modifications and alterations will occur to others upon a reading and understanding of this specification and drawings. The inventions are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof,

Claims

1. A powder coating applicator that receives powder coating material from a powder coating supply to apply the powder coating material to an article, the powder coating applicator comprising: a body portion having a powder coating material inlet adapted to receive powder coating material from the powder coating supply; and a diverter having a first operating mode during which powder coating material flows from said inlet to a first coating material outlet for a coating operation, and a second operating mode during which powder coating material flows from said inlet to a second coating material outlet for a non-coating operation. wherein the powder coating applicator is mounted on a device that reciprocates the first coating material outlet into and out of the interior of the article.

2. The powder coating applicator according to claim 1 further comprising a control that operates to select whether the powder coating material flows toward the article being coated or flows to said second coating material outlet.

3. The powder coating applicator according to claim 1 further comprising a pump connected to the second coating material outlet.

4. The powder coating applicator according to claim 3 wherein the pump is turned off in the first operating mode and turned on in the second operating mode.

5. The powder coating applicator according to claim 1 wherein in the non-coating operation, powder coating material is recycled from the powder coating applicator back to the powder coating supply.

6. The powder coating applicator according to claim 1 further comprising a powder concentrating device attached to the body portion, the powder concentrating device adapted to increase the powder-to-air ratio of the air-entrained powder exiting the body portion.

7. The powder coating applicator according to claim 6 wherein the powder concentrating device comprises an inlet that receives powder coating material from the body portion and an outlet, the outlet of the powder concentrating device having a smaller diameter than the inlet of the powder concentrating device.

8. The powder coating applicator according to claim 7 wherein the powder concentrating device further comprises a powder condenser outlet located between the powder concentrating device inlet and the powder concentrating device outlet adapted to remove air from the powder coating material and air mixture supplied from the body portion.

9. The powder coating applicator according to claim 6 wherein the powder concentrating device defines a conical flow passage between the device inlet and the device outlet.

10. The powder coating applicator according to claim 1 wherein cycling the powder coating applicator between the first operating mode and the second operating mode creates a pulsed powder spray output from the applicator.

1 1. The powder coating applicator according to claim 1 wherein the powder coating applicator is in the first operating mode during a part of the time that the first coating material outlet of the powder coating applicator is being reciprocated into and out of the article.

12. The powder coating applicator according to claim 1 1 wherein the powder coating application device in the second operating mode during a part of the time that the first coating material outlet is being reciprocated into and out of the article.

13. The powder coating applicator according to claim 1 wherein the article is mounted on a device that moves the article past the powder coating applicator.

14. The powder coating applicator according to claim 1 wherein the diverter further comprises an extension having an inner conduit defining a third powder material outlet and an outer conduit that defines a passage between the inner conduit and the outer conduit, wherein the second powder material outlet is connected to the passage, and wherein in the second operating mode, powder coating material is conveyed from the third powder material outlet, through the passage and the second powder material outlet to the powder coating supply.

15. A powder coating applicator that receives powder coating material from a powder coating supply to apply the powder coating material to an article, the powder coating applicator comprising: a body portion having a powder coating material inlet adapted to receive powder coating material from the powder coating supply; a diverter having a first operating mode during which powder coating material flows from said inlet to a first coating material outlet for a coating operation, and a second operating mode during which powder coating material flows from said inlet to a second coating material outlet for a non-coating operation; and a powder concentrating device attached to the body portion, the powder concentrating device adapted to increase the powder-to-air ratio of the air-entrained powder exiting the body portion.

16. The powder coating applicator according to claim 15 wherein the powder concentrating device comprises an inlet that receives powder coating material from the body portion and an outlet, the outlet of the powder concentrating device having a smaller diameter than the inlet of the powder concentrating device.

17. The powder coating applicator according to claim 16 wherein the powder concentrating device further comprises a powder condenser outlet located between the powder concentrating device inlet and the powder concentrating device outlet adapted to remove air from the powder coating material and air mixture supplied from the body portion.

18. The powder coating applicator according to claim 15 wherein the powder concentrating device defines a conical flow passage between the device inlet and the device outlet.

19. The apparatus of according to claim 15 wherein the powder coating applicator is mounted on a device that reciprocates the first coating material outlet into and out of the interior of the article

20. The apparatus of according to claim 15 further comprising a pump in fluid communication with the second coating material outlet for drawing the powder coating material from the applicator and directing the powder coating material back to the supply.

21. The powder coating applicator according to claim 15 wherein the diverter further comprises an extension having an inner conduit defining a third powder material outlet and an outer conduit that defines a passage between the inner conduit and the outer conduit, wherein the second powder material outlet is connected to the passage, and wherein in the second operating mode, powder coating material is conveyed from the third powder material outlet, through the passage and the second powder material outlet to the powder coating supply.

22. The powder coating applicator according to claim 15 wherein cycling the powder coating applicator between the first operating mode and the second operating mode creates a pulsed powder spray output from the applicator.

23. The powder coating applicator according to claim 15 further comprising a pump connected to the second coating material outlet, wherein the pump is turned off in the first operating mode and turned on in the second operating mode.

24. A powder coating applicator that receives powder coating material from a powder coating supply to apply the powder coating material to an article, the powder coating applicator comprising: a body portion having a powder coating material inlet adapted to receive powder coating material from the powder coating supply; a powder concentrating device attached to the body portion, the powder concentrating device adapted to increase the powder- to-air ratio of the air-entrained powder exiting the body portion; and a first powder coating outlet adapted to receive the concentrated air-entrained powder from the powder concentrating device for coating the article, wherein the powder coating applicator is mounted on a device that reciprocates the first coating material outlet into and out of the interior of the article.

25. The powder coating applicator according to claim 24 wherein the powder concentrating device includes an inlet adapted to that receive powder coating material from the body portion, and an outlet adapted to convey powder coating material to the first powder material outlet, the powder concentrating device further including a powder condenser outlet located between the device inlet and the device outlet to remove air from the powder-air mixture supplied from the body portion.

26. The powder coating applicator according to claim 25 wherein the powder concentrating device defines a conical flow passage between the device inlet and the device outlet.

27. The powder coating applicator according to claim 24 further comprising a diverter having a first operating mode during which powder coating material flows from said inlet to the first coating material outlet for a coating operation, and a second operating mode during which powder coating material flows from said inlet to a second coating material outlet for a non-coating operation.

28. The powder coating applicator according to claim 27 wherein the diverter further comprises an extension having an inner conduit defining a third powder material outlet and an outer conduit that defines a passage between the inner conduit and the outer conduit, wherein the second powder material outlet is connected to the passage, and wherein in the second operating mode, powder coating material is conveyed from the third powder material outlet, through the passage and the second powder material outlet to the powder coating supply.

29. The powder coating applicator according to claim 28 wherein the first powered material outlet is recessed in the outer conduit.

30. The powder coating applicator according to claim 28 wherein the passage between the outer conduit and the inner conduit is generally annular.

31. The powder coating applicator according to claim 27 further comprising a pump connected to the second powder coating outlet to draw powder coating material from the powder coating applicator.

32. The powder coating applicator according to claim 27 wherein the pump is turned off in the first operating mode and turned on in the second operating mode.

33. The powder coating applicator according to claim 27 wherein cycling the powder coating applicator between the first operating mode and the second operating mode creates a pulsed powder spray output from the applicator.

34. A method for applying a powder coating material to an article, comprising: conveying powder coating material from a powder hopper to a powder coating applicator having a first powder coating outlet and a second powder coating outlet; operating the powder coating applicator in a first operating mode in which powder coating material flow is directed to the first coating material outlet during a coating operation; operating the powder coating applicator in the second operating mode in which powder coating material is directed to a second coating material outlet in a non-coating operation; and reciprocating an end of the powder coating applicator into and out of the interior of the article.

35. The method according to claim 34 further comprising cycling the powder coating applicator between the first operating mode and the second operating mode to produce a pulsed flow of powder exiting the powder applicator device.

36. The method according to claim 34 further comprising mounting the article on a device and moving the device to move the article past the powder coating applicator.

37. The method according to claim 34 wherein the powder coating applicator is operated in the first operating mode during a part of the time that the extension is being reciprocated into and out of the interior of the article.

38. The method according to claim 34 wherein the powder coating applicator is operated in the second mode of operation during a part of the time that the extension is being reciprocated into and out of the article.

39. The method according to claim 34 further comprising turning a pump on to switch from the first operating mode to the second operating mode.

40. The method according to claim 34 wherein, in the second operating mode, a circulation loop for powder coating material is formed from the powder hopper, through the powder coating applicator, and back to the powder hopper.

41. The method according to claim 34 further comprising removing air from the powder-air mixture delivered to the powder coating applicator prior to the powder coating material exiting the first powder material outlet.

42. A method for applying a powder coating material to an article, comprising: conveying powder coating material from a powder hopper to a powder coating applicator having a first powder coating outlet; removing air from the powder-air mixture delivered to the powder coating applicator prior to the powder coating material exiting the first powder material outlet; and reciprocating an end of the powder coating applicator into and out of the interior of the article.

43. The method according to claim 42 further comprising operating the powder coating applicator in a first operating mode in which powder coating material flow is directed to the first coating material outlet during a coating operation; and operating the powder coating applicator in the second operating mode in which powder coating material is directed to a second powder material outlet in a non-coating operation.

44. The method according to claim 43 further comprising cycling the powder coating applicator between the first operating mode and the second operating mode to produce a pulsed flow of powder exiting the powder applicator device.

45. The method according to claim 43 wherein the applicator is operated in the second operating mode at least a portion of the time the powder outlet is in the interior of the article to remove powder that does not adhere to the interior of the article.

46. The method according to claim 43 further comprising turning a pump on to switch from the first operating mode to the second operating mode.

47. A method for applying a powder coating material to an article, comprising: conveying powder coating material from a powder hopper to a powder coating applicator having a first powder coating outlet and a second powder coating outlet; operating the powder coating applicator in a first operating mode in which powder coating material flow is directed to the first coating material outlet during a coating operation; operating the powder coating applicator in the second operating mode in which powder coating material is directed to a second coating material outlet in a non-coating operation; and removing air from the powder-air mixture delivered to the powder coating applicator prior to the powder coating material exiting the powder material.

48. The method according to claim 47 further comprising cycling the powder coating applicator between the first operating mode and the second operating mode to produce a pulsed flow of powder exiting the powder applicator device.

49. The method according to claim 47 further comprising reciprocating an end of the powder coating applicator into and out of the interior of the article.

50. The method according to claim 47 wherein, in the second operating mode, a circulation loop for powder coating material is formed from the powder hopper, through the powder coating applicator, and back to the powder hopper.