US 20060193731 A1
A paint system containing at least one pump 150 and at least one paint mixing vessel 160. At least one return line 46 functions to route paint from the paint system back into the paint mixing vessel from whence it was drawn. At least one eductor 522 fluidly communicates with a respective paint mixing vessel 160 and a respective return line 46 whereby during operation of the paint system, as paint traverses through return line 46 and into eductor 577, paint is drawn from the respective paint mixing vessel 160 thereby mixing the paint drawn from the vessel with the paint in the return line 46.
1. A paint system comprising:
at least one paint mixing vessel containing paint;
at least one pump for circulating a paint stream drawn from the mixing vessel;
at least one return line for passage of the paint stream; and
at least one eductor in fluid communication with said at least one paint mixing vessel, and said at least one pump, and said at least one return line,
whereby in operation, paint is pumped through said at least one return line through said at least one eductor, thereby drawing paint from said at least one paint mixing vessel and mixing said paint stream within said at least one return line with said drawn paint.
2. The paint system of
a second paint mixing vessel containing paint;
a second pump for circulating a second paint stream drawn from the second mixing vessel;
a second return line for passage of the second paint stream; and
a second eductor in fluid communication with said second paint mixing vessel, and said second pump, and said second return line,
whereby in operation, paint is pumped through said second return line through said second eductor, thereby drawing paint from said second paint mixing vessel and mixing said second paint stream with said drawn paint.
3. The paint system of
a plurality of paint mixing vessels, each vessel containing paint;
a plurality of pumps wherein each pump in said plurality of pumps corresponds to a respective paint mixing vessel and each paint mixing vessel corresponds to a respective paint stream, each of said pumps employed for circulation of said respective paint stream drawn from each respective mixing vessel;
a plurality of return lines wherein each return line corresponds to a respective paint mixing vessel for passage of a respective paint stream for circulation thereof; and
a plurality of eductors wherein each eductor fluidly communicates with a corresponding one of said plurality of return lines, and each eductor fluidly communicates with a corresponding paint mixing vessel,
wherein during operation of said paint system, each eductor draws paint from a respective paint mixing vessel for mixing within a respective paint stream within a respective return line.
4. A method of mixing paint within a paint system, the method comprising the steps of:
pumping a first paint stream from a mixing vessel through the paint system;
circulating the paint first paint stream through the system into a first paint return line in fluid communication with the mixing vessel; and
passing the first paint stream through an eductor in fluid communication with the mixing vessel to draw paint from the mixing vessel and thereby mix the drawn paint with paint being circulated in the return line.
In large paint finishing facilities, paint materials are delivered to application points through a network of distribution pipes. The paint is generally pumped through the pipes from a central location (paint mix room or paint kitchen) designed for handling and storage of flammable and combustible liquids (e.g., solvent-based paints and/or water-based paints.) Various types of pumps are used for this purpose. The paint materials are adjusted to proper viscosity for application and contained in tanks connected to the pumps.
The paint is continually circulated between the mix room and the application points to prevent settling of pigments and metallic particles or similar appearance enhancers (mica, etc.) in the distribution pipes, which would result in sub-standard finish appearance on the painted product. Paint tank agitation methods commonly used to maintain mixing of the paint within the paint mixing vessel may employ a series of paddles, propeller, or serrated disks (
The components of conventional paint agitation systems are generally bulky and expensive, and frequent, complex, and expensive maintenance procedures may be required to maintain these components in working order. Furthermore, the drive mechanism or motor for each agitator increases the cost of operating the paint system as well as increasing the maintenance requirements for the overall system. In particular, systems with multiple paint colors require an agitation means for each paint pot of the system. As the number of paint pots increase within a given system, the operating cost increases accordingly.
Paint circulating system 510 includes a paint mix tank 518 for storing and mixing of the paint, a paint application area 512 (for example, a paint spray booth), at least one paint supply line 514 for conveying paint from mix tank 518 to paint application area 512, and at least one paint recovery or return line 516 for conveying paint from application area 512 to mix tank 518. Circulation of paint between mix tank 518 and application area 512 is provided and managed by a paint flow regulation system, generally designated 515.
Paint flow regulation system 515 comprises an arrangement of known elements, such as pumps, valves, pressure regulators, compressed air lines, and other components necessary for regulating flow of the paint between a paint reservoir (such as mix tank 518 of the present invention) and paint application area 512, in accordance with design requirements of the paint system. One example of such a flow regulation system is disclosed in U.S. Pat. No. 5,389,149, incorporated herein by reference. Numerous other known configurations of flow regulation system are possible and would be suitable for regulating paint flow in the paint circulating system described herein, depending on design requirements.
Paint recovery line 516 provides a conduit for conveying unused paint from paint application area 512 back to mix tank 518. In the embodiment shown in
The present invention uses the circulated paint returning to mix tank 518 to agitate the tank contents, using Coanda or Venturi effect eductors to amplify the volume of the returning paint to maintain required agitation of the tank contents, thereby eliminating or reducing the need for separate agitation devices. Referring again to
The design and positioning of eductors 522 are optimized to produce a high turbulence in mixing tank 518 to prevent settling of pigments and metallic particles or similar appearance enhancers. Eductors 522 are known liquid eductors for agitating chemicals in tanks. One example of a suitable liquid eductor is manufactured by Fox Valve Development Corp. of Dover, N.J. In a Venturi-type eductor, for example, the paint is forced through a narrow or restricted area in the eductor, resulting in an increase in the speed of paint flow. The increased speed results in a reduction in pressure adjacent the accelerated fluid flow. This causes air to be pushed into the lower pressure regions, thereby injecting air into the paint stream. By injecting air into the returning paint stream, the volume of the returning paint stream is amplified, helping to maintain required agitation of the mix tank contents. In this manner, eductors 522 are effective for maintaining a high liquid turbulence in mix tank 518 to prevent settling of pigments and metallic particles or similar appearance enhancers.
In certain applications, a paint mixture having highly pigmented constituents and dense settling characteristics may need supplemental agitation to overcome settling. Also, because of variable production requirements and variables that exist in the operation of paint mix facilities, it may be necessary to provide additional, mechanical agitation of select tanks. Thus, in an alternative embodiment of the paint circulating system (shown in
The apparatus and principles set forth above may be applied to any suitable paint reservoir to provide needed agitation of the paint mixture.
The present invention offers several advantages. Use of eductors as set forth herein may obviate the need for conventional agitation systems. Thus, the present invention may enable the elimination (or a substantial reduction in the number) of expensive conventional agitation system components, such as explosion-proof electric agitator motors, explosion-proof wiring, and agitator motor starters and controls. Elimination or reduction of these components reduces agitation system maintenance time and associated costs, system power consumption, and system power feeds.
Exemplary Paint System
Various paint systems are known in the art. In accordance with the present invention, and for example only, a description of a paint system incorporating the agitation means or mechanism of the present invention is described below.
The paint system 20 comprises a plurality of color changers 30 through 44 that are connected, in series relationship, by, for example, fourteen (14) discrete paint lines 46 through 59. A paint line is provided for each color accommodated by the system. Thus, in the disclosed and constructed embodiment of the invention, fourteen (14) colors can be accommodated by the system 20. However, for purposes of clarity, only one line 46 is shown connecting the color changers 30 through 44 in series.
The color changers 30 through 44 are provided with solenoid valve panels 60 through 74, respectively, located exteriorly of the spray booth 22 which, in turn, are controlled by push buttons on a like plurality of push button panels 76 through 90, respectively, located internally of the spray booth 22.
Each of the color changers 30 through 44 services a spray gun 100 through 114, respectively, through discrete flexible paint supply lines 120 through 134, respectively.
Paint is supplied to the system 20 through, for example, the line 46 from a pump 150. It is to be understood that each of the paint lines 46 through 59 is supplied by a separate pump. Only the pump 150, paint line 46 and their associated supply and control system is discussed herein for purposes of clarity.
The pump 150 is energized by compressed air supplied thereto from a line 152 through a solenoid valve 154, pressure regulator 156, and flexible air line 158. Paint is supplied to the pump 150 from a paint pot 160 of, for example, 10 gallon capacity, through a ball valve 162 and flexible line 164. The pump 150 supplies paint under pressure to the line 46 through a check valve 166, flexible paint line 168, ball valve 170, and solenoid valve 172.
Paint is returned through a return portion of line 46 from the color changers 30 through 44, through a ball valve 180, back pressure regulator 182, flow meter 184, flexible paint return line 186, and ball valve 188 to the paint pot 160. The diaphragm of the back pressure regulator 182 is loaded by air pressure from the air line 152 through a regulator 190 and solenoid valve 192.
The system 20 is flushed by aerated solvent or foam produced in a turbulator 200. Aerated solvent flows from the turbulator 200 under the control of solenoid valves 230 and 232 for the solvent, and solenoid valves 234 and 236 for the air. The solvent flows through a line 238 to a bank of solenoid valves 240 through 266 and through a line 270 to a bank of solenoid valves 272 through 296, the function of which will be described hereinafter.
The paint system 20 is conditioned for painting of a given color by connecting the paint supply hose 164 between the pump 150 and the paint supply solenoid 162 of a paint pot 160, containing a desired color. The paint return hose 186 is then connected from the flow meter 184 to the paint return ball valve 188 on the paint pot 160. The paint pot valves 162 and 188 are then opened.
The system 20 is electronically conditioned for start by entering a vehicle number, a paint code number, and paint line number into a conventional process control computer (PC). As a vehicle 24 enters the spray booth 22 a conventional encoder (EC) transmits vehicle position to the control computer. The computer will search its memory for the appropriate paint which has previously been loaded into a specific paint pot 160 of the paint system 20. When the paint number is found, the computer (PC) energizes the pump 150 and appropriate push button lights at each of the paint station push button consoles 76 through 90. Paint circulates continuously in line 46 through the color changers 30 through 44. In the example illustrated in the drawings, the push buttons at each console 76 through 90 would be lit that control the paint line 46. When the operator pushes any lighted push button at any console 76 through 90, paint flows from the associated color changer 30 through 44, respectively, to its associated spray gun. It is to be noted that in the example, only the lighted push buttons controlling line 46 can be activated.
After a predetermined spraying interval, the painter can either energize stop buttons on his associated control console 76 through 90 or the tracking logic in the encoder (EC) and computer (PC) shuts off the color valves controlling line 46 in the color changers 30 and 44.
Spray Gun Line Flush
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After the paint line has been cleared of paint, and as seen in
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In accordance with the present invention, at least one eductor 522 is positioned in line with the paint return line 46, and also in fluid communication with the paint mixing vessel 160. As paint fluid flows through line 46 it necessarily draws paint from the paint pot 160 and then directs the fluid into the paint pot 160 as determined by design criteria. For example, the fluid flowing through paint return line 46 may be directed to the bottom of the paint pot 160 thereby providing an aggressive agitation of the paint within paint pot 160. It will be appreciated that each paint return line associated with a given color may contain an eductor/mixer 522 if desired thereby decreasing the overall energy requirements of the paint system. Stated another way, in operation, a paint system of the present invention contains at least one paint pot, at least one pump circulating at least one paint stream drawn from the at least one paint pot, and at least one eductor in fluid communication with both the at least one pump and the at least one paint pot. It will be further appreciated that
In further accordance with the present invention and with the description given above, a method of mixing paint within a paint vessel is characterized by first providing a paint source within a mixing vessel, then circulating or pumping a paint stream, then returning the paint stream through an eductor in fluid communication with the mixing vessel to draw paint from the mixing vessel, then returning the paint stream and the drawn paint to the mixing vessel. It should be appreciated that a paint system an a method of mixing a plurality of paint streams within the paint system is defined as containing a plurality of paint streams may be independently pumped from a corresponding plurality of paint mixing vessels, whereby each of said plurality of paint streams is routed through one of a corresponding plurality of eductors by pumping said paint stream through one of a corresponding plurality of pumps. Accordingly, a plurality of paint lines is provided wherein each paint line incorporates an eductor fluidly communicating with a paint pump, a paint mixing vessel, and a paint return line, thereby providing an improved method of mixing paint.
It should be understood that the preceding is merely a detailed description of various embodiments of this invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. The preceding description, therefore, exemplifies but should not be construed to limit the scope of the invention.