Patent Application
20080047591
Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use herein of “including”, “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof, as well as additional items and equivalents thereof.
Referring now more specifically to the drawings and to
Applicator 10 includes a main body portion 14 having an atomizing head 16 on the forward end thereof. Head 16 includes a rotary bell cup 18 and a shaping air system 20 (
Referring now more specifically to
Bell cup 18 in the exemplary embodiment shown is a cup or bowl-like body rotatable about its axis. Bell cup 18 has an interior surface 40 and an exterior surface 42. The cup-like shape of exemplary bell cup 18 provides a relatively narrow base end 44 and a broader forward end 46 terminating at a forward edge 48; however, it should be understood that bell cups of other shapes, such as, for example, substantially cylindrical shapes, also can be used advantageously in conjunction with the present invention. Interior surface 40 is substantially smooth, and expands outwardly from base end 44 to forward edge 48. Exterior surface 42 is also smooth, and expands outwardly from base end 44.
Shaping air system 20 includes a ring of shaping air inner nozzles 60 directed at exterior surface 42 near base end 44, and a ring of shaping air outer nozzles 62 directed forwardly adjacent forward end 46. Inner nozzles 60 are positioned behind bell cup 18, near base end 44 and are oriented in a manner such that a first pattern of inner fluid streams 64 is directed toward bell cup 18, from behind base end 44. In the exemplary arrangement shown, inner nozzles 60 are provided at evenly spaced locations, in a substantially circular pattern, behind and slightly outwardly of base end 44. Inner fluid streams 64 emitted from inner nozzles 60 approach exterior surface 42, and attach to surface 42 to follow along surface 42 toward forward end 46 and forward edge 48. As inner fluid streams 64 advance each stream follows the surface to which it attaches, and leaves exterior surface 42 at forward edge 48.
Outer nozzles 62 are disposed behind bell cup 18 and radially outward therefrom. Outer nozzles 62 are oriented in a manner such that a pattern of outer fluid streams 66 is directed forwardly toward the area at which inner fluid streams 64 separate from forward edge 48.
Fluids control system 12 is a flow control means for controlling flow of cleaning fluids to the interior and exterior of bell cup 18. Fluids control system 12 includes an air supply 80, a solvent supply 82 and a controller 84. Air supply 80, solvent supply 82 and controller 84 are connected to an inner shaping air valve set 86, an outer shaping air valve set 88, a coating supply valve set 90 and a dedicated cleaning nozzle valve set 92. One or more cleaning nozzle 94 is disposed behind bell cup 18 and directs a cleaning fluid spray 96 against exterior surface 42. In the exemplary embodiment spray 96 is aimed nearer base end 44 than forward end 46, but those skilled in the art will understand that spray 96 can be aimed at other positions along exterior surface 42 as well, and two or more cleaning nozzles 94 can be used aimed at different locations on exterior surface 42.
Air supply 80 is a source of pressurized air that can be the same source of pressurized air used to operate air turbine 32 and/or can be the source of pressurized air for shaping air supplied to nozzles 60, 62. Alternatively, air supply 80 can be a different source of pressurized air. Air supply 80 is connected in fluid flow communication to inner nozzles 60 through a conduit 100 and an air supply valve 102 in inner shaping air valve set 86. Air supply 80 is connected in fluid flow communication to outer fluid nozzles 62 through a conduit 104 and an air supply valve 106 in outer shaping air valve set 88. Further, air supply 80 is connected in fluid flow communication to coating supply tube 34 via an air supply valve 108 in coating supply valve set 90. Additionally, air supply 80 is connected in flow communication to cleaning nozzle 94 through a conduit 110 via an air supply valve 112 in cleaning nozzle valve set 92.
Solvent supply 82 is a source of solvent suitable for the coating being applied by applicator 10, to dilute and remove the coating from surfaces of applicator 10 which the coating contacts. Solvent supply 82 is connected in fluid flow communication to inner fluid nozzles 60 through conduit 100 and a solvent supply valve 120 in inner shaping air valve set 86. Solvent supply 82 is connected in fluid flow communication to outer fluid nozzles 62 through conduit 104 and a solvent supply valve 122 in outer shaping air valve set 88. Further, solvent supply 82 is connected in fluid flow communication to coating supply tube 34 via a solvent supply valve 124 in coating supply valve set 90. Additionally, solvent supply 82 is connected in flow communication to cleaning nozzle 94 through conduit 110 via a solvent valve 126 in cleaning nozzle valve set 92.
Air supply valves 102, 106, 108 and 112 and solvent supply valves 120, 122, 124 and 126 control the flow of air and a solvent, respectively, from the supplies there of to inner nozzles 60, outer nozzles 62, tube outlet 36 and cleaning nozzle 94, respectively. Each of the valves can be opened or closed independently of the others by operating signals from controller 84 to enable or block flow of the respective fluid, air or solvent, from the source thereof to the downstream nozzles 60, 62, 94 and outlet 36. Controller 84 can be a logic based analog or digital controller or simple electric controls for selectively opening and closing air supply valves 102, 106, 108 and 112 and solvent supply valves 120, 122, 124 and 126. Accordingly, controller 84 is connected to valves 102, 106, 108 and 112 and solvent supply valves 120, 122, 124 and 126 via signal lines 130, 132, 134, 136, 138, 140, 142 and 144, respectively. Those skilled in the art will understand readily that signals transmitted from controller 84 to air supply valves 102, 106, 108 and 112 and solvent supply valves 120, 122, 124 and 126 can be in the form of electrical signals, fluid signals in the way of pneumatic, hydraulic or other pressure signals or the like, and signal lines 130, 132, 134, 136, 138, 140, 142 and 144 can be electrical or other signal carrying wire-like signal lines, hydraulic lines or the like suitable for the signal being transmitted. Wireless communication from a transmitter that is connected to controller 84 to receivers associated with the valves also can be used.
During the application of coating, bell cup 18 is spun at high velocity through the operation of turbine 32, in known manner. Coating material, such as paint, is supplied from a source thereof (not shown) via supply tube 34 to the inside of bell cup 18 and is deposited on interior surface 40. Centrifugal force acting on the coating material causes the material to move along interior surface 40 toward forward edge 48. As the coating material advances off forward edge 48, the acceleration of the coating material is forward and outward relative to bell cup 18.
Shaping air system 20 is operated to confine the spray pattern of coating material being ejected from forward edge 48 and thereby improve the transfer efficiency of the coating being applied to an object being coated. As known to those skilled in the art, pressurized air is provided to inner nozzles 60 and outer nozzles 62 via conduits 100 and 104, respectively. Fluid streams 64 comprising air from inner nozzles 60 approach and attach to exterior surface 42, following along exterior surface 42 toward forward edge 48. Inner fluid streams 64 thereby operate against the coating material immediately as the coating material leaves forward edge 48. The spray pattern is confined and controlled immediately. Air streams 64 establish a barrier, or resistance to further outward expansion of the spray pattern ahead of bell cup 18. Pressurized air is also provided to outer nozzles 62 and outer fluid streams 66 comprising air directed from nozzles 62 toward forward end 46 of bell cup 18 reinforce the control from inner air streams 64 to control, confine and shape the pattern of coating moving toward the object to be coated.
As necessary, cleaning is performed in accordance with the present invention. Cleaning can be performed periodically to minimize build up, or, if coating materials are changed cleaning can be performed to prevent contamination of the new coating material with residue from the previous coating material. To perform a cleaning operation, the supply of coating to supply tube 34 is terminated. Air and solvent from air supply 80 and solvent supply 82, respectively, are provided via valve sets 86, 88, 90 and 92 for cleaning purposes. It should be understood that the cleaning processes to be described can be performed simultaneously or successively, and cleaning of exterior surface 42 can be performed less frequently than cleaning of the interior surface 40, if desired.
To clean interior surface 40, valves 108 and 124 are operated via control from controller 84, to provide alternating discharges of air and solvent. The air and solvent are not mixed, but are provided in bursts or pulses, one after another. Dilution of the film coating is performed by solvent and the diluted material is forced away by a following air blast. Additional discharges of air and solvent can follow to perform the desired cleaning. Pulsing air and solvent in this manner, referred to herein as an “air/solvent chop”, can cause vibrations in supply tube 34. These vibrations commonly referred to as “hammering,” serve to dislodge hardened or thickening accumulations of coating material, thereby performing an aggressive scrubbing action to clean the passage through supply tube 34, and the surfaces of distributing body 38 and interior surface 40.
Similarly, air supply valve 102 and solvent supply valve 120 of inner shaping air valve set 86 are pulsed in an air/solvent chop via control signals from controller 84 to provide alternating bursts or pulses of air and solvent through conduit 100 to inner shaping nozzles 60. The alternating bursts of air and solvent clean inner shaping nozzles 60, around and in which coating may have accumulated and interfered with air flow for shaping purposes. The hammering effect of the air/solvent chop dislodges coating that may have accumulated in nozzles 60. Additionally, the air and solvent emitted from inner shaping nozzles 60 attach to and follow exterior surface 42 for cleaning coating that may have deposited thereon.
Outer fluid nozzles 62 are cleaned in a similar manner. Valves 106 and 122 are opened and closed under control of controller 84 to provide successive, alternating bursts or pulses of air and solvent in an air/solvent chop. The alternating bursts of air and solvent clean outer fluid nozzles 62, around and in which coating may have accumulated and interfered with air flow for shaping purposes. The hammering effect of the air/solvent chop dislodges coating that may have accumulated in nozzles 62. Additionally, the air and solvent emitted from outer fluid nozzles 62 attach to and clean forward end 46 near forward edge 48, so that fluid flow off forward edge 48 and adjacent thereto are not impacted adversely by coating accumulation.
Supplying air and solvent to inner nozzles 60 and outer nozzles 62 cause the nozzles to remain open and clear so that the desired pattern of shaping air is emitted during coating application. The desired coating pattern control is retained by keeping fluid nozzles 60, 62 and forward edge 48 clean and free from accumulation. Effective cleaning with an air/solvent chop may require only minimal time. If exterior surface 42 requires additional cleaning, additional volumes of air and solvent spray 96 can be emitted from dedicated cleaning nozzle 94 via conduit 110. Valves 112 and 126 are opened and closed under control of controller 84 to provide successive, alternating bursts of air and solvent in an air/solvent chop. In one advantageous arrangement, cleaning nozzle 94 is positioned near base and 44 and provides a fan-like spray on exterior surface 42. It should be understood however that more than a single nozzle can be provided, and a single or multiple nozzles can be positioned to provide air and solvent at other positions on exterior surface 42, such as closer to forward end 46. Further, other emission patterns from such cleaning nozzles can be used. The particular arrangement shown is merely exemplary.
The periods of air and solvent supply during one air/solvent chop cycle can be varied, as can the number of cycles used in a cleaning procedure to obtain optimum cleaning. It is anticipated that the “air on” portion of a cycle often will be of shorter duration than the “solvent on” portion of the cycle, although the cycle portions can be of equal duration or with longer “air on” cycle portions as well. For example, for some paints it is believed a “solvent on” portion of one cycle may last about 1.7 seconds, and the “air on” portion of the cycle may last about 0.4 second; and that 3 or 4 cycles will be used. It is also contemplated that in some situations an overlap of the air and solvent portions of the cycle may be used; however, the predominant portion of the cycle will be air or solvent only during an air/solvent chop cleaning cycle. The hammering effect of the air/solvent chop cycle can be optimized by locating valve sets 86, 88, 90 and 92 close to the applicator so that the effect is not dampened significantly before reaching the passage or orifice to be cleaned. It may be advantageous to integrate the valve sets into the applicator to enhance the scrubbing action.
It should be understood that a single cycle in and air/solvent chop may begin with a burst of air to force coating through an opening or off a surface, or the cycle may begin with a burst of solvent for immediate dilution and washing, followed by an air blast for purging. As part of the cleaning process, fluids control system 12 can be operated to provide a mixture of air and solvent for a gentler cleaning of tube 34, distributing body 38, interior surface 40 and exterior surface 42.
Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.
Various features of the invention are set forth in the following claims.
This Non-Provisional Application claims the benefit of U.S. Provisional Application No. 60/840,083 filed Aug. 25, 2006.
| Number | Date | Country | |
|---|---|---|---|
| 60840083 | Aug 2006 | US |
