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Patent Searching and Data


Title:
POWDER PAINT TRANSPORT SYSTEM AND METHOD
Document Type and Number:
WIPO Patent Application WO/2006/084253
Kind Code:
A2
Abstract:
An assembly for applying a powdery substance to an article includes a receiver fluidly connected to a source of the powdery substance for receiving the powdery substance under pressure and having a receiver fluidizer for maintaining the powdery substance in a fluidized state. A feed transporter is fluidly connected to the receiver for receiving the powdery substance from the receiver and having a transporter fluidizer maintaining the powdery substance in a fluidized state. A powder applicator is fluidly connected to the feed transporter for receiving the powdery substance under pressure and applying the powdery substance to an article. An equalizer interconnecting the receiver to the feed transporter for equalizing a gas pressure between the receiver and the feed transporter while the powdery substance is being transferred to the feed transporter from the receiver.

Inventors:
KLOBUCAR JOSEPH M (US)
PAKKALA JAMES L (US)
COLE DAVID J (US)
Application Number:
PCT/US2006/004219
Publication Date:
August 10, 2006
Filing Date:
February 03, 2006
Export Citation:
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Assignee:
DURR SYSTEMS INC (US)
KLOBUCAR JOSEPH M (US)
PAKKALA JAMES L (US)
COLE DAVID J (US)
International Classes:
B05B1/24
Foreign References:
US4900199A
US4669921A
US5615832A
US6176647B1
US4613259A
Attorney, Agent or Firm:
Degrazia, Gregory D. (P.C. Suite 101, 39400 Woodward Avenu, Bloomfield Hills Michigan, US)
Download PDF:
Claims:
CLAIMS
1. What is claimed is: A method of transporting a powdery substance to an applicator from a source of the powdery substance for application to an article, comprising the steps of: providing a receiver for receiving the powdery substance from said source of the powdery substance and a feed transporter for receiving the powder substance from said receiver hopper; transferring the powdery substance under pressure from said sourced of the powdery substance to said receiver; substantially equalizing a gas pressure between said receiver and said feed transporter; transferring the powdery substance from said receiver to said feed transporter when the gas pressure between said receiver and said feed transporter have substantially equalized; and transferring the powdery substance from said feed transporter to said applicator once a predetermined amount of powdery substance has been transferred from said receiver to said feed transporter.
2. The method as set forth in claim 1, wherein said step of transferring the powdery substance from said receiver to said feed transporter under pressure is further defined by maintain a substantially equal pressure between said receiver and said feed transporter while transporting the powdery substance.
3. The method as set forth in claim 1, further including the step of opening a valve disposed in an equalization line between said receiver and said feed transporter while transferring the powdery substance between said receiver and said feed transporter thereby maintaining equal pressure between said receiver and said feed transporter while transporting the powdery substance.
4. The method as set forth in claim 1, further including the step of fluidizing the powder substance disposed inside said receiver.
5. The method as set forth in claim 1, further including the step of fluidizing the powdery substance disposed inside said feed transporter.
6. The method as set forth in claim 1, further including the step of providing a source of pressurized air disposed between said feed transporter and said applicator for assisting transporting the powdery substance between said feed transporter and said applicator under pressure.
7. The method as set forth in claim 1, further including the step of venting the receiver during transferring the powdery substance from said source of powdery substance to said receiver.
8. The method as set forth in claim 7, further including the step of terminating venting said receiver during said step of substantially equalizing the gas pressure between said receiver and said feed transporter.
9. The method as set forth in claim 1, wherein said step of transferring the powdery substance from said source of powdery substance to said receiver is further defined by transferring less than a quantity of powdery substance known to fill said receiver.
10. The method as set forth in claim 1, wherein said step of transferring the powdery substance from said receiver to said feed transporter is further defined by transferring the powdery substance from said receiver to said feed transporter after the gas pressure between said receiver and said feed transporter is substantially equalized.
11. The method as set forth in claim 1 , wherein said step of transferring the powdery substance from said receiver to said feed transporter is further defined by transferring the powdery substance from said receiver to said feed transporter with gravitational forces.
12. An assembly for applying a powdery substance to an article, comprising: a receiver fluidly connected to a source of the powdery substance for receiving the powdery substance under pressure and having a receiver fluidizer for maintaining the powdery substance in a fluidized state; a feed transporter fluidly connected to said receiver for receiving the powdery substance from said receiver and having a transporter fluidizer maintaining the powdery substance in a fluidized state; a powder applicator fluidly connected to said feed transporter for receiving the powdery substance under pressure and applying the powdery substance to an article. an equalizer interconnecting said receiver to said feed transporter for equalizing a gas pressure between said receiver and said feed transporter while the powdery substance is being transferred to said feed transporter from said receiver.
13. An assembly as set forth in claim 12, including an equalization line having an equalization valve disposed between said receiver and said feed transporter and being operable for equalizing a gas pressure between said receiver and said transporter while transporting the powdery substance from said receiver to said transporter.
14. An assembly as set forth in claim 12, including a feed line having a feed valve disposed between said receiver and said feed transporter being operable for transferring the powdery substance from said receiver to said feed transporter.
15. An assembly as set forth in claim 12, including a vent line having a vent valve disposed between a vent gas destination and said receiver for venting gas from said receiver while transferring the powdery substance from said source of the powdery substance to said receiver.
16. An assembly as set forth in claim 12, including a back pressure line having a back pressure regulator disposed between said vent line and said equalization line for regulating the gas pressure in said feed transporter and said receiver.
17. An assembly as set forth in claim 16, wherein said back pressure regulator maintains a gas pressure in said receiver and said feed transporter generally below 15 psig.
18. An assembly as set forth in claim 12, including an applicator line having an applicator valve disposed between said feed transporter and said applicator for regulating the powdery substance from said feed transporter to said applicator.
19. An assembly as set forth in claim 16, including a push air line providing pushing air to said applicator line for assisting the transport of the powdery substance to said applicator.
20. An assembly as set forth in claim 12, wherein said gas pressure between said receiver and said feed transporter is maintained at greater than ambient air pressure.
21. An assembly as set forth in claim 12, wherein the gas pressure between said receiver and said feed transporter is maintained generally below 15 psig.
22. An assembly as set forth in claim 12, wherein said applicator is disposed in an applicator housing and said vent line is fluidly connected to said applicator housing.
Description:
DENSE PHASE FINAL POWDER PAINT TRANSPORT SYSTEM AND METHOD

FIELD OF THE INVENTION [00001] This invention relates to a powdery substance transport system and a method of transporting a powdery substance in bulk phase to an applicator. More specifically, this invention relates to a dense phase powder paint transport system for transporting powder paint to a paint applicator disposed within a paint application housing. BACKGROUND OF THE INVENTION

[00002] The use of powdery substances in manufacturing operations has increased in recent years, primarily due to the restrictions placed by various government agencies upon volatile emissions vented to the atmosphere. The application of powdery substances such as, for example, powder paint, is gaining wider acceptance in vehicle manufacturing as powder paint applied to vehicle bodies inside the powder paint application housing typically has a complete absence of volatile emissions. At a typical application facility, powder paint is received in a primary hopper having a fluidized bed to maintain the powder paint in a fluidized state and is then delivered to a remote location having a final feed hopper connected to one or a plurality of paint applicators. The transportation of the powder paint is performed by vacuum dilute phase equipment as disclosed, for example, in United States Patent No. 6,679,193 where vacuum pumps are used to create negative pressure within a powder receiver unit associated with a primary hopper to draw virgin powder material from a source of the powder material into the powder receiver unit. A second vacuum pump applies a negative pressure in each powder receiver unit associated with the feed hoppers so the powder material from the primary hopper located at a remote location is drawn through long transfer lines into the powder receiver units associated with the feed hoppers adjacent the powder application booth. The powder receiver units at the powder application housing fill respective feed hoppers with the powder paint, which in turn is transferred from the

feed hoppers at powder pumps to the powder applicators inside the powder application booth.

[00003] While the use of vacuum pumps to create negative pressures within the various hoppers has gained widespread use, it is also exceedingly expensive due to the number of vacuum pumps required to create vacuums within the various hoppers. Furthermore, the transport of the powdered paint using negative pressure lends itself to line blockages if the negative pressure is not continuously maintained at a necessary level. Still further, a complicated valve arrangement is required at a location between the applicator and the feed hoppers where the powder has been transferred at a negative pressure and must be provided to the applicator at a positive pressure. Therefore, it would be desirable to provide a new apparatus and method for transporting powdery substance, such as, for example, powder paint, between a source of the powdery substance and an applicator in a simplified cost-effective manner.

SUMMARY OF THE INVENTION

[00004] The present application discloses the method and apparatus for transporting a powdery substance from a source of the powdery substance to an applicator for applying the powdery substance to an article. A receiver is fluidly connected to a source of the powdery substance for receiving the powdery substance under pressure from the source. The receiver has a fluidizer for maintaining the powdery substance in a fluidized state while under pressure. The feed transporter receives the powdery substance from the receiver and includes a transporter fluidizer for maintaining the powdery substance in a fluidized state while under pressure. A powder applicator is fluidly connected to the feed transporter for receiving the powdery substance under pressure and applying the powdery substance to an article. The equalizer is interconnected to the receiver and the feed transporter for equalizing a gas pressure between the receiver and the feed transporter while the powdery substance is being transferred to the feed transporter from the receiver. One method contemplated by the inventors for transferring the powdery substance from the receiver to the feed transporter is through gravitational forces, which is facilitated by the fluidized state of the powdery substance and, furthermore,

eliminates the need for a transfer pump disposed between the receiver and the feed transporter.

[00005] The use of positive pressure and gravitational forces to transfer the powdery substance between the various fluidized containers and subsequently to the applicator solves the problems associated with the prior art, negative pressure, transport systems as disclosed in prior art patents. For example, reduction in the requisite apparatus, such as, for example, negative pressure pumps, reduces the capital expense associated with the prior art systems. Furthermore, the fluidized state of the powdery substance being transferred under positive pressure reduces the propensity of the prior art, negative pressure, transport systems to plug and block the lines disposed between the various hoppers. Accordingly, there is an industrial need to provide a simplified, more reliable system and method for transporting a powdery substance between a source of the powdery substance and an applicator in a manufacturing setting.

BRIEF DESCRIPTION OF THE DRAWING

[00006] Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[00007] Figure 1 is a schematic view of the inventive dense phase powdery substance transport system.

DETAILED DESCRIPTION OF THE INVENTION [00008] Referring to Figure 1, a schematic view of the inventive powdery substance transport system is generally shown at 10. A source of the powdery substance 12 is connected to a receiver 14 by receiver fill line 16. The powdery substance contemplated for the present invention is powder paint used to coat articles, such as, for example, motor vehicle bodies and components in the absence of a release of volatiles to the environment. A receiver fill valve 18 is disposed within the receiver fill line 16 between the receiver 14 and the source 12

for controlling when the powdery substance is transferred to the receiver 14 from the source 12 as will be described further below.

[00009] The receiver 14 includes a receiver fluidizer 20 having a fluidizing plate 22 with a porous composition as is known to those of skill in the art. A source of fluidizing air 24 provides air to the fluidizer 20 beneath the fluidizing plate 22 providing fluidizing air to the receiver 14 to maintain a powdery substance in a fluidized state. Other types of fiuidizers may also be used as is known to those of skill in the art. The receiver 14 is generally maintained at a positive pressure of up to 15 psig, the purpose of which will become more evident as described further below.

[00010] A feed transporter line 26 connects the receiver 14 to a feed transporter 28 for transferring the powdery substance from the receiver 14 to the feed transporter 28. A feed fill valve 30 is disposed in the feed transporter line 26 between the receiver 14 and the feed transporter 28 for controlling the amount of powdery substance transferred from the receiver 14 to the feed transporter 28. The feed transporter 28 includes a feed transporter fluidizer 32 having a fluidizing plate 34. the feed transporter fluidizer 32 is connected to a source of fluidizing air 24 for maintaining the powdery substance in a fluidized state within the feed transporter 28 in a similar manner as the receiver 14 as discussed above. Other types of known fiuidizers may also be used as is known to those of skill in the art. The feed transporter 28 is maintained at a positive pressure, generally below about 15 psig.

[00011] It is contemplated by the inventors that the receiver 14 is disposed above the feed transporter 28 so that gravitational forces cause the fluidized powdery substance disposed in the receiver 14 to flow into the feed transporter 28, where the powdery substance is also maintained in a fluidized state. To transport the powdery substance with gravitational forces, the receiver has a cone shaped bottom (not shown) leading to the feed transfer line 26. However, it should be understood that assist air or a positive pressure pump (not shown) may be used to facilitate the transport of the powdery substance from the receiver 14 to the feed transporter 28.

[00012] It is preferable that the gas pressure in the receiver 14 is generally the same as that in the feed transporter 28 to facilitate the transfer of the

powdery substance. To maintain a similar pressure between the receiver 14 and the feed transporter 28 an equalization line 36 interconnects, preferably an upper end of the feed transporter 28 to an upper end of the receiver 14. To substantially equalize the gas pressure between the receiver 14 and the feed transporter 28 during the transfer of the powdery substance from the receiver 14 to the feed transporter 28, an equalization valve 38 opens to allow gas to pass between the receiver 14 and the feed transporter 28.

[00013] A vent line 40 connects the receiver 14 to a vent air destination 42 to maintain the receiver below generally 15 psig or other preferred positive pressure. The vent air destination 42 is contemplated to be either a specific destination where any powdery substance that may have escaped from the receiver 14 is filtered prior to the vent air entering the atmosphere or an application housing 44 where reclamation hoppers are used to transfer reclaimed powdery substance to the source 12 or an equivalent reclaim source (not shown). A vent valve 46 controls the venting of the air from the receiver 14 through the vent line 40 as will be explained further below.

[00014] A back pressure line 48 vents air from the equalization line

36, or in the alternative, the top of the feed transporter 28 into the vent line 40 to regulate the equalized gas pressure below about 15 psig, or other predetermined pressure between the receiver 14 and the feed transporter 28. A back pressure regulator 50 is disposed in the back pressure line 48, and preferably comprises a pressure actuated valve 51 having a set point of about 15 psig or other predetermined positive pressure for maintaining the equalized gas pressure between the receiver 14 and the feed transporter 28. [00015] An applicator line 52 connects the feed transporter 28 to a powder applicator 54 disposed within the applicator housing 44 to apply the powdery substance to the articles also disposed within the applicator housing 44. An applicator valve 56 is disposed between the applicator 54 and the feed transporter 28 to control the flow of the powdery substance through the applicator line 52. The applicator valve 56 opens when an article is being applied in the applicator housing 42 by the applicator 54 and closes when application is terminated. Because the feed transporter is maintained at a positive pressure, and

the applicator 54 is disposed at an ambient pressure, a pump is not required to transport the powdery substance through the applicator line 52 to the applicator 54. However, it is contemplated by the inventors that an assist, push air source 58 may be necessary to assist pushing the powdery substance through the applicator line 52, and therefore, is connected to the applicator line 52 by a push air line 60. The push air line 60 intercepts the applicator line 52 preferably between the applicator valve 56 and the applicator 54.

[00016] During operation, a sequence of about four steps takes place to fill the receiver 14, equalize the receiver 14 with the feed transporter 28, fill the feed transporter 28, and close the feed fill valve 30 for transporting the powdery substance through the applicator line 52 to the applicator 54. The process set forth above is conducted through a number of sequential steps where an air lock is created through the closing of the various valves 18, 30, 38, 46, and 56, which is generally dictated by the need to apply the powdery substance to an article disposed within the applicator housing 44.

[00017] While filling the receiver 14, the powdery substance is delivered under pressure to the receiver 14 through the receiver fill line 16 from the source 12. Preferably, less powdery substance is delivered into the receiver 14 from the source 12 than is required to fill the receiver 14 to avoid overflowing the receiver into the vent line 40 or the equalization line 36. The powdery substance is delivered through the receiver fill line 16 by a flow of pressurized air. The pressurized air exits through the vent line 40 while the powdery substance accumulates in the main body of the receiver 14 and is fluidized by the fluidizer 20. As set forth above, the air flowing through the vent line 40 is delivered to a vent air destination 42 or the applicator housing 44 in case a residual amount of powdery substance is drawn into the vent line 40.

[00018] While the receiver 14 is being filled, the receiver fill valve 18 is open, the vent valve 46 is open, the equalization valve 38 is closed, and the feed valve 30 is closed. Furthermore, fluidization air 24 is provided to both the receiver 14 and the feed transporter 28. Generally, about 60 seconds is required to fill the receiver 14 with the powdery substance. Of course, the volume of the receiver 14, the diameter of the receiver fill line 16, and the gas pressure pushing the powdery

substance through the receiver fill line 16 impacts the duration of the time required to fill the receiver 14.

[00019] Once a desired amount of powdery substance is delivered to the receiver 14, the gas pressure of the receiver 14 is equalized with the gas pressure of the feed transporter 28. During equalization, the receiver fill valve 18 and the vent valve 46 are closed while the equalization valve 38 is opened. This sequence allows the air pressure in the receiver 14 and the feed transporter 28 to equalize. Preferably, the equalization line 36 is sized so that the duration of the gas pressure equalization between the receiver 14 and the feed transporter 28 takes about 15 seconds. This is considered a slow equalization rate to allow the pressure in the feed transporter 28 to remain generally constant. If the equalization of the gas pressure between the receiver 14 and the feed transporter 28 occurs too rapidly, the pressure in the feed transporter 28 drops excessively fast adversely affecting the fluidization of the powdery substance inside the feed transporter 28. During equalization, the feed fill valve 30 also remains closed. Furthermore, the fluidizing air 24 remains open to fluidize the receiver 14 and the feed transporter 28.

[00020] Once the gas pressure of the receiver 14 has been equalized with the gas pressure of the feed transporter 28, the feed fill valve 30 is opened while the equalization valve 38 remains open and the vent valve 46 and the receiver fill valve 18 remain closed. When the feed fill valve 30 opens, the fluidized powdery substance flows through, preferably, gravitational forces into the feed transporter 28 from the receiver 14. However, as stated above, positive pressure pumps or additional air pressure may be used to assist the transfer of the powdery substance from the receiver 14 to the feed transporter 28. A load cell 62 interacts with the feed transporter 28 in a known manner to determine the amount of powdery substance disposed in the feed transporter.

[00021] Once the feed transporter 28 has been filled to an appropriate level with the powdery substance, the feed fill valve 30 is closed and the receiver fill valve 18 and the receiver vent valve 46 are opened to relieve the pressure in the receiver 14 in preparation of transferring a new amount of powdery substance from the source 12 to the receiver 14. It is contemplated by the inventors that the duration of feeding the feed transporter 28 with the powdery substance through the

feed transporter line 26 will take approximately 45 seconds. However, the size of the feed transporter line 26 can be varied to adjust the duration required to transfer the required amount of powdery substance to the feed transporter 28 from the receiver 14. [00022] Once the fluidizing air 24 has increased the gas pressure inside the feed transporter 28 to a desired level, the applicator valve 56 is opened and the positive pressure inside the feed transporter 28 forces the fluidized powdery substance through the applicator line 52 to the powder applicator 54. It should be understood that a number of applicator lines 52 and applicator valves 56 may be increased if a plurality of powder applicators 54 are desired within the applicator booth 44. In this manner, the powdery substance and compressed air is directed to the various applicators 54 through a plurality of applicator lines 52.

[00023J The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

[00024] Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for convenience and are not to be in any way limiting, the invention may be practiced otherwise than as specifically described.