Methods and apparatus for applying powder to workpieces

• US 5,612,096 A
• Filed: 04/25/1995
• Issued: 03/18/1997
• Est. Priority Date: 06/30/1992
• Status: Expired due to Fees

• Current Assignee: Nordson Corporation
• Original Assignee: Nordson Corporation
• Inventors: Matsunaga, Masafumi, Pleuse, Harald, Mulder, Douglas C., Macartney, Lawrence J., Pintelon, Joseph, Niemiec, Ronald E., Scarbrough, Don R.
• Primary Examiner(s): Beck, Shrive
• Assistant Examiner(s): PARKER, FREDERICK JOHN
• Application Number:
  US08/428,026
• Time in Patent Office: 693 Days
• Field of Search: 427/180, 427/181, 427/195, 427/232, 427/234, 427/235, 427/236, 427/239, 427/421, 427/466, 427/476, 427/478, 427/475, 427/8, 427/477
• US Class Current: 427/466
• CPC Class Codes: B05B 1/06 in annular, tubular or hollow conical form
• CPC Class Codes: B05B 1/265 the liquid or other fluent material being symmetrically deflected about the axis of the nozzle
• CPC Class Codes: B05B 12/004 comprising sensors for monitoring the delivery, e.g. by displaying the sensed value or generating an alarm B05B12/08 takes precedence; registering or indicating the condition or the working of machines or other apparatus in general G07C3/00
• CPC Class Codes: B05B 12/06 for effecting pulsating flow nozzles, spray head or outlet with means for generating a discharge of pulsating nature B05B1/08
• CPC Class Codes: B05B 13/0242 the objects being individually presented to the spray heads by a rotating element, e.g. turntable
• CPC Class Codes: B05B 13/0609 the hollow bodies being automatically fed to, or removed from, the machine
• CPC Class Codes: B05B 14/10 the excess material being particulate for spray booths B05B14/48
• CPC Class Codes: B05B 14/30 comprising enclosures close to, or in contact with, the object to be sprayed and surrounding or confining the discharged spray or jet but not the object to be sprayed
• CPC Class Codes: B05B 15/55 using cleaning fluids
• CPC Class Codes: B05B 5/032 for spraying particulate materials
• CPC Class Codes: B05B 5/047 using tribo-charging
• CPC Class Codes: B05B 7/1454 comprising means for supplying collected oversprayed particulate material spray booth with arrangements for collecting oversprayed material B05B14/40
• CPC Class Codes: B05B 7/1486 for spraying particulate material in dry state

Abstract

An apparatus for spraying powder coating material includes a rotatable turret which moves articles to and from a work station. A powder spray gun is operable to spray a pattern onto each of the articles in turn while the article is at the work station. The powder flows through the spray gun as a series of pulses. A diverter assembly is operable to divert a portion of each pulse of powder away from the nozzle to more sharply define the pulse. An excess powder collector draws a flow of powder away from the work station. A virgin powder container supplies powder to a powder collector container which supplies powder to a powder feed container which supplies powder to the spray gun. Sensors associated with the virgin, collector and feed containers ensure that a predetermined quantity of powder is maintained in each container. During transport of powder from the virgin and collector containers, the containers and their associated pumps are vibrated to facilitate the flow of powder. The powder spray gun is mounted on a three axis adjustment assembly to enable the powder spray gun nozzle to be accurately positioned relative to an article at the work station.

Claims

1. A method of sequentially applying powder to each article of a plurality of articles, said method comprising the steps of sequentially forming a series of pulses of air with powder entrained therein, sequentially conducting each of the pulses of air with powder entrained therein along a flow path through a spray gun toward a work station where powder is applied to each of the articles in turn, and sequentially diverting a portion of each of the pulses of air with powder entrained therein from the flow path through the spray gun to sharply define an edge portion of each of the pulses of air with powder entrained therein.

2. A method as set forth in claim 1 wherein said step of sequentially diverting a portion of each of the pulses of air with powder entrained therein from the flow path includes diverting a trailing end portion of each of the pulses of air with powder entrained therein from the flow path.

3. A method as set forth in claim 1 further including the step of electrostatically charging the powder in each of the pulses of air with powder entrained therein in turn during sequential movement of each of the pulses of air with powder entrained therein along the flow path through the spray gun, said step of diverting a portion of each of the pulses of air with powder entrained therein from the flow path being performed after performing said step of electrostatically charging the powder in each of the pulses of air with powder entrained therein.

4. A method as set forth in claim 1 further including the steps of conducting a flow of air with excess powder entrained therein away from the work station.

5. A method as set forth in claim 4 further including the steps of providing a fusible element in the path of flow of air with excess powder entrained therein away from the work station and providing an output signal in response to the fusible element being fused by exposure to heat in the path of flow of air with excess powder entrained therein.

6. A method as set forth in claim 1 wherein said step of sequentially forming a series of pulses of air with powder entrained therein includes operating a pump to induce a flow of air with powder entrained therein along the flow path through the spray gun and repeatedly interrupting operation of the pump, said step of diverting a portion of each of the pulses of air with powder entrained therein being performed contemporaneously with interrupting operation of the pump.

7. A method of comprising the steps of sequentially moving a plurality of can lids to and from a work station, and spraying an annular band of powder onto a major side surface of each of the can lids in turn at the work station, said step of spraying an annular band of powder onto a surface of each of the can lids in turn includes maintaining a nozzle in a spaced apart relationship with each of the can lids while conducting a flow of air with powder entrained therein from the nozzle toward the major side surface of each of the can lids along a flow path which has an annular cross sectional configuration in a plane which extends perpendicular to a central axis of the flow path, maintaining a space circumscribed by the flow path substantially free of powder, and, while continuing to maintain the nozzle in a spaced apart relationship with the can lids, depositing the powder on the major side surface of each of the can lids in turn in an annular band which circumscribes an area on the major side surface of the can lid which is substantially free of powder.

8. A method as set forth in claim 7 further including the steps of diverting a flow of air with powder entrained away from the nozzle upon completion of spraying of an annular band of powder onto each of the can lids in turn.

9. A method comprising the steps of sequentially moving a plurality of articles to and from a work station and spraying powder onto a surface of each of the articles in turn at the work station, said step of spraying powder onto a surface of each of the articles in turn includes operating a pump to induce a flow of air with powder entrained therein toward a nozzle along a flow path extending between the pump and the nozzle, interrupting operation of the pump to interrupt the flow of powder along the flow path between the pump and the nozzle, and, contemporaneously with performance of said step of interrupting operation of the pump, operating a diverter from an inactive condition in which the diverter is ineffective to effect the flow of air with powder entrained therein toward the nozzle to an active condition in which the diverter is effective to induce a flow of air with powder entrained therein from the flow path extending between the pump and the nozzle, said step of sequentially moving articles to and from a work station includes initiating movement of each of the articles in turn away from the work station while the diverter is in the active condition.

10. A method as set forth in claim 9 further including the step of electrostatically charging the powder in the flow of air with powder entrained therein, said step of operating a diverter from an inactive condition to an active condition includes inducing a flow of air with electrostatically charged particles of powder entrained therein away from the nozzle.

11. A method a set forth in claim 9 wherein said step of spraying powder onto a surface of each of the articles in turn includes maintaining the nozzle in a spaced apart relationship with each of the articles while conducting a flow of air with powder entrained therein from the nozzle toward the surface of each of the articles along a flow path which has an annular cross sectional configuration in a plane which extends perpendicular to a central axis of the flow path, maintaining a space circumscribed by the flow path substantially free of powder, and, while continuing to maintain the nozzle in a spaced apart relationship with the articles, depositing the powder on the surface of each of the articles in turn in an annular band which circumscribes an area on the surface of the article which is substantially free of powder.

12. A method of sequentially applying powder to each article of a plurality of articles, said method comprising the steps of sequentially forming pulses of air with powder entrained therein at a first location, conducting a flow of the pulses of air with powder entrained therein along a flow path which extends from the first location to a nozzle, electrostatically charging powder in each of the pulses of air with powder entrained therein during sequential flow of the pulses of air with powder entrained therein through a charging location disposed along the flow path between the first location and the nozzle, diverting a first portion of each of the pulses of air with powder entrained therein from the flow path at a location disposed along the flow path between the charging location and the nozzle, and sequentially directing a second portion of each of the pulses of air with powder entrained therein from the nozzle toward each of the articles in turn.

13. A method as set forth in claim 12 wherein said step of sequentially directing a second portion of each of the pulses of air with powder entrained therein from the nozzle toward each of the articles in turn includes maintaining the nozzle in a spaced apart relationship with each of the articles and sequentially shaping the second portion of each of the pulses of air with powder entrained therein to have an annular cross sectional configuration in a plane which extends perpendicular to a path of flow of the second portion of each of the pulses of air with powder entrained therein from the nozzle, said method further includes sequentially depositing the powder in the second portion of each of the pulses of air with powder entrained therein on the surface of each of the articles in an annular band which circumscribes an area on the surface of the article which is substantially free of powder.

14. A method as set forth in claim 12 further including the steps of conducting a flow of air with powder entrained therein away from the flow path of pulses of air with powder entrained therein, providing a fusible element in the path of flow of air with powder entrained therein away from the flow path of pulses of air with powder entrained therein, and providing an output signal in response to the fusible element being fused by exposure to heat.

15. A method comprising the steps of sequentially moving a plurality of can lids to and from a work station, and spraying an annular band of powder onto a major side surface of each of the can lids in turn at the work station, said step of spraying an annular band of powder onto a major side surface each of the can lids in turn includes conducting a flow of air with powder entrained therein from a nozzle toward the major side surface of each of the can lids in turn along a flow path which extends transverse to the major side surface of the can lid while maintaining the nozzle in a spaced apart relationship with the can lid, said step of conducting a flow of air with powder entrained therein toward a major side surface of each of the can lids in turn includes conducting a flow of air with powder entrained therein through a space between the nozzle and the major side surface of each of the can lids in turn along a flow path which has an annular cross sectional configuration in a plane which extends perpendicular to a central axis of the flow path, said step of conducting a flow of air with powder entrained therein along a flow path which has an annular cross sectional configuration includes maintaining a central space circumscribed by the flow of air with powder entrained therein substantially free of powder and maintaining the nozzle in a spaced apart relationship with a can lid toward which the flow of air with powder entrained therein is conducted, and depositing the powder in an annular band on the major side surface of each of the can lids in turn with the major side surface of the can lid extending from a location adjacent to an outer periphery of the annular band of powder across a space circumscribed by the annular band of powder.

16. A method as set forth in claim 15 further including the steps of electrostatically charging powder in the flow of air with powder entrained therein before the flow of air with powder entrained therein enters the nozzle, conducting the flow of air with electrostatically charged powder entrained therein to the nozzle during performance of said step of spraying an annular band of powder onto a major side surface of each of the can lids in turn, and diverting the flow of air with electrostatically charged powder entrained away from the nozzle upon completion of spraying of an annular band of powder onto the major side surface of each of the can lids in turn and after having performed said step of electrostatically charging powder in the flow of air with powder entrained therein.

17. A method as set forth in claim 15 wherein said step of spraying an annular band of powder onto the major side surface of each of the can lids in turn includes operating a pump to induce a flow of air with powder entrained therein toward the nozzle during the spraying of an annular band of powder onto the major side surface of one of the can lids, interrupting operation of the pump to interrupt the flow of powder toward the nozzle, and, contemporaneously with performance of said step of interrupting operation of the pump, operating a diverter from an inactive condition in which the diverter is ineffective to effect the flow of powder toward the nozzle to an active condition on which the diverter is effective to induce a flow of air with powder entrained therein away from the nozzle, said step of sequentially moving can lids to and from a work station includes initiating movement of the one can lid away from the work station while the diverter is in the active condition.

18. A method as set forth in claim 15 wherein said step of spraying an annular band of powder onto a major side surface of each of the can lids in turn includes producing a series of pulses of air with powder entrained therein, said step of conducting a flow of air with powder entrained therein from a nozzle toward a major side surface of each of the can lids in turn includes conducting a first portion of each of the pulses of air with powder entrained therein from the nozzle toward the major side surface of each of the can lids in turn and diverting a second portion of each of the pulses of air with powder entrained therein away from the nozzle before the second portion of each of the pulses of air with powder entrained therein can be conducted from the nozzle toward a can lid.

19. A method as set forth in claim 15 wherein said step of spraying an annular band of powder onto each of the can lids in turn includes conducting powder from a container to the nozzle, said method further including at least partially filling the container with powder, said step of at least partially filling the container with powder includes vibrating a sieve and conducting powder through the sieve while vibrating the sieve.

20. A method as set forth in claim 15 further including conducting a flow of air with excess powder entrained therein away from the major side surface of each of the can lids in turn at the work station to an excess powder collector while maintaining the excess powder collector in a spaced apart relationship with the major side surface of each of the can lids.

21. A method as set forth in claim 20 further including the steps of conducting a flow of air with excess powder entrained therein away from the excess powder collector to a receiving location, providing a fusible element in the flow of air with excess powder entrained therein and providing an output signal in response to the fusible element being fused by exposure to heat in the path of flow of air with excess powder entrained therein.