Method and system for cleaning a paint supply line and changing paint colors in production paint operations

• US 5,221,047 A
• Filed: 08/13/1991
• Issued: 06/22/1993
• Est. Priority Date: 08/13/1991
• Status: Expired due to Fees

• Current Assignee: Fanuc Robotics America Incorporated (Fanuc Corporation)
• Original Assignee: Gmfanuc Robotics Corporation
• Inventors: Akeel, Hadi A.
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): TRAINOR, CHRISTOPHER
• Application Number:
  US07/744,361
• Time in Patent Office: 679 Days
• Field of Search: 427/421, 118/302, 118/408, 15/3.5, 15/3.51, 134/22.11, 239/104, 239/123, 239/112
• US Class Current: 239/123
• CPC Class Codes: B05B 12/1481 comprising pigs, i.e. movable elements sealingly received in supply pipes, for separating different fluids, e.g. liquid coating materials from solvent or air cleaning pipes with pigs B08B9/0557, pigs per se F16L55/26
• CPC Class Codes: B08B 9/055 the cleaning devices conforming to, or being conformable to, substantially the same cross-section of the pipes, e.g. pigs or moles pigs or moles per se F16L55/26; their launching and detection F16L55/46; separating pigs in pipelines F17D3/00
• CPC Class Codes: B08B 9/0551 Control mechanisms therefor

Abstract

Method and system are provided for cleaning a paint supply line and changing paint colors by inserting and propelling a termination piston or slug having an outer diameter which forms a sliding fit within the supply line to wipe paint off the interior walls of the supply line. Preferably, the supply line is elastic and the termination piston squeegees the paint off the interior walls. In order to more fully clean the supply line prior to changing paint colors, a predetermined amount of cleaning fluid such as a solvent is injected into the supply line behind the termination piston from a common passage of a manifold. A leading piston or slug is then inserted immediately ahead of a new paint color in the supply line. The pistons may be disposable or may be reused by recirculating them by means of shuttle assemblies and a return line. The manifold is fitted with various valves to selectively supply pressurized air, solvent and two or more paint colors to the supply line. The shuttle assemblies are also fitted with valves to shuttle the pistons between the supply and return lines. A process controller controls the timing of the valves of the manifold and the shuttle assemblies. The method and system can also be used to retrofit existing color changers in an economical yet environmentally sound fashion.

Claims

1. In a method for the productive utilization of substantially all paint in a paint supply line, interior walls of the supply line having substantially constant inside diameter, the method including the steps of inserting a termination piston within the supply line, propelling the termination piston through the supply line so as to cause the termination piston to push the paint through the supply line, and removing the termination piston from the supply line after the step of propelling, the improvement comprising:

the termination piston is reusable and wherein the method further includes the steps of;

providing a piston return line;

inserting the removed termination piston into the piston return line;

propelling the termination piston through the piston return line;

removing the termination piston from the piston return line after the step of propelling the termination piston through the piston return line; and

inserting the termination piston back into the supply line to allow the termination piston to again push the paint through the supply line.

2. In a method for changing paint colors using a paint system having a paint supply line, applicator means being fed with paint by the supply line and a first source of pressurized paint of a first color and a second source of pressurized paint of a second color adapted to be selectively connected to the supply line, interior walls of the supply line having a substantially constant inside diameter, the method including the steps of connecting the supply line to the first source of pressurized paint, disconnecting the supply line from the first source of pressurized paint, feeding the paint in the supply line to the applicator means, inserting a termination piston within the supply line after the step of disconnecting, propelling the termination piston through the supply line so as to cause the termination piston to wipe paint off the interior walls of the supply line, removing the termination piston from the supply line after the step of propelling, and connecting the supply line to the second source of pressurized paint, the improvement comprising the additional steps of:

connecting the supply line to a source of cleaning fluid to cause cleaning fluid to enter the supply line after the step of inserting;

disconnecting the supply line from the source of cleaning fluid when the amount of cleaning fluid in the supply line is sufficient to dissolve any residue paint remaining on the interior walls of the supply line after the termination piston has wiped the interior walls; and

inserting a leading piston substantially identical to said termination piston into the supply line after the step of disconnecting the supply line from the source of cleaning fluid and before the step of connecting the supply line to the second source of paint.

3. The method of claim 2 wherein the cleaning fluid includes a solvent.

4. The method of claim 2 further comprising the steps of connecting the supply line to a source of compressed gas to cause compressed gas to enter the supply line after the step of inserting the leading piston and disconnecting the supply line from the source of compressed gas when the amount of compressed gas in the supply line is sufficient to propel the leading piston a predetermined amount.

5. The method of claim 2 further comprising the steps of propelling at least a portion of the cleaning fluid in the supply line through the applicator means.

6. The method of claim 5 further comprising the step of depositing the remainder of cleaning fluid in the supply line into a sump.

7. The method of claim 2 wherein the applicator means includes a paint atomizer.

8. The method of claim 2 further comprising the steps of:

propelling the leading piston through the supply line; and

removing the leading piston from the supply line after the step of propelling the leading piston.

9. The method of claim 8 wherein the termination and leading pistons are reusable and wherein the method further comprises the steps of:

providing a return line;

inserting the removed termination and leading pistons into the return line;

propelling the termination and leading pistons through the return line;

removing the termination and leading pistons from the return line after the step of propelling the termination and leading pistons through the return line; and

inserting the termination and leading pistons back into the supply line to allow the paint system to again change paint colors.

10. The method of claim 8 wherein the leading piston is propelled by the second color paint.

11. The method of claim 8 further comprising the step of depositing at least a portion of the cleaning fluid into a sump by virtue of the leading piston being propelled through the supply line.

12. A paint color change system for supplying paint to an applicator means, the system comprising individual pressurized sources for at least first and second color paints, manifold means having a common passage for connecting said individual pressurized paint sources to a paint supply line adapted to feed the paint to said applicator means, interior walls of the supply line having a substantially constant inside diameter, valve means for selectively coupling said individual paint sources to said manifold, and a controller connected to said valve means and controlling operation thereof, the improvement comprising:

a termination piston having an exterior surface with an outside diameter which forms a sliding fit within the supply line;

means for inserting the termination piston within the supply line;

means for removing the termination piston from the supply line wherein the controller is also connected to said means for inserting and to said means for removing and controls operation thereof so that after one of said sources of two paints is connected to said applicator means, the termination piston is inserted into the common passage and said supply line followed by the connection of the supply line to the second source of paint so as to fill the supply line with the second color paint to allow said applicator means to again paint an article, the second color paint propelling the termination piston through the supply line so as to cause the surface of the termination piston to wipe the first color paint off the interior walls of the supply line; and

an individual source of pressurized cleaning fluid, the common passage of the mainfold means connecting the source of pressurized cleaning fluid to the supply line and the valve means selectively coupling the source of pressurized cleaning fluid to said manifold, the controller controlling the valve means to introduce an amount of cleaning fluid into the common passage and the supply line sufficient to dissolve any residue of said first color paint remaining on the interior walls of the supply line after the termination piston has squeegeed the interior walls.

13. The system of claim 12 wherein the supply line is elastic relative to the surface of the termination piston and wherein the termination piston squeegees the first color paint off the interior walls of the supply line by virtue of the elasticity of the supply line.

14. The system of claim 12 further comprising means for depositing at least a portion of the removed paint into a paint sump by virtue of the termination piston being propelled through the supply line.

15. The system of claim 12 wherein the surface of the termination piston is made from a low friction material.

16. The system of claim 12 wherein the cleaning fluid includes a solvent.

17. The system of claim 16 further comprising a leading piston substantially identical to said termination piston, the controller controlling the means for inserting so that after the amount of cleaning fluid is introduced, the leading piston is inserted into the common passage before the supply line is connected to the second source of paint.

18. The system of claim 17 further comprising an individual source of compressed gas, the common passage of the manifold means connecting the source of compressed gas to the supply line and the valve means selectively coupling the source of compressed gas to said manifold, the controller controlling the valve means to introduce an amount of compressed gas into the common passage sufficient to propel the leading piston a predetermined amount within the common passage.

19. The system of claim 12 wherein said valve means selectively couples said supply line to a sump, the controller controlling the operation thereof to deposit the cleaning fluid in the supply line into the sump.

20. The system of claim 12 wherein the applicator means includes a paint atomizer.

21. The system of claim 17 wherein the leading piston is propelled through the supply line by the second color paint and wherein the controller controls the means for removing so that after the leading piston is propelled through the supply line the means for removing removes the leading piston from the supply line.

22. The system of claim 21 wherein the means for inserting is a first shuttle assembly, the means for removing is a second shuttle assembly and the termination and leading pistons are reusable and wherein the system further comprises:

a return line adapted to feed the termination and leading pistons from the second shuttle assembly to the first shuttle assembly;

means for propelling the termination and leading pistons through the return line; and

the controller connected to the first and second shuttle assemblies and the means for propelling the pistons through the return line and controlling the operation thereof so that;

the second shuttle assembly removes the termination and leading pistons from the supply line and inserts the termination and leading pistons into the return line;

and the first shuttle assembly removes the termination and leading pistons from the return line after the termination and leading pistons are propelled through the return line; and

inserts the termination and leading pistons into the common passage to allow the paint system to again change paint colors.

23. The system of claim 21 wherein the valve means selectively couples said supply line to a sump, the controller controlling the operation thereof to deposit at least a portion of the cleaning fluid into the sump by virtue of the leading piston being propelled through the supply line.

24. A paint color change system for supplying paint to an applicator means, the system comprising individual pressurized sources for at least first and second color paints, manifold means having a common passage for connecting said individual pressurized paint sources to a paint supply line adapted to feed the paint to said applicator means, interior walls of the supply line having a substantially constant inside diameter, valve means for selectively coupling said individual paint sources to said manifold, and a controller connected to said valve means and controlling operation thereof, the improvement comprising:

a termination piston having an exterior surface with an outside diameter which forms a sliding fit within the supply line;

means for inserting the termination piston within the supply line;

means for removing the termination piston from the supply line wherein the controller is also connected to said means for inserting and to said means for removing and controls operation thereof so that after one of said sources of two paints is connected to said applicator means, the termination piston is inserted into the common passage and said supply line followed by the connection of the supply line to the second source of paint so as to fill the supply line with the second color paint to allow said applicator means to again paint an article, the second color paint propelling the termination piston through the supply line so as to cause the surface of the termination piston to wipe the first color paint off the interior walls of the supply line wherein the means for inserting is a first shuttle assembly, the means for removing is a second shuttle assembly and the termination piston is reusable and wherein the system further comprises;

a return line adapted to feed the termination piston from the second shuttle assembly to the first shuttle assembly;

means for propelling the termination piston through the return line; and

the controller being connected to the first and second shuttle assemblies and the means for propelling the termination piston through the return line and controlling the operation thereof so that;

the second shuttle assembly removes the termination piston from the supply line and inserts the termination piston into the return line; and

the first shuttle assembly removes the termination piston from the return line after the termination piston is propelled through the return line and inserts the termination piston back into the supply line to allow the termination piston to again wipe the paint off the interior walls of the supply line.

25. The system of claim 24 wherein at least one of the shuttle assemblies includes a double acting piston having an internal cavity and adapted to be actuated by pressurized fluid to index between first and second position thus connecting its internal cavity to the supply line in the first position and to the return line in the second position thus affecting the transfer of the piston from one line to the other line.

26. The system of claim 24 wherein at least one of the shuttle assemblies includes a rotary barrel having multiple cavities and indexed to stop at successive angular locations to position each cavity successively opposite to the supply line then to the return line thus affecting the transfer of the piston from one line to the other line.

27. The system of claim 24 wherein at least one of the shuttle assemblies includes a linearly moving piston having an internal cavity.

28. The system of claim 24 wherein at least one of the shuttle assemblies has multiple cavities.

29. The system of claim 24 wherein at least one of the shuttle assemblies includes a rotary barrel having multiple cavities.

30. A method for changing paint colors, cleaning and productively utilizing paint in a paint supply line of a high volume production paint system, the system having applicator means being fed with the paint by the supply line and a first source of pressurized paint of a first color, a source of pressurized cleaning fluid adapted to be selectively connected to the supply line and a second source of pressurized paint of a second color adapted to be selectively connected to the supply line, interior walls of the supply line having a substantially constant inside diameter, the method comprising the steps of:

connecting the supply line to the first source of pressurized paint to fill the supply line with the first color paint to allow the applicator means to paint an article;

feeding the paint in the supply line to the applicator means;

disconnecting the supply line from the first source of pressurized paint when the remaining paint in the supply line is sufficient to complete the painting of the article;

inserting a first termination piston having an exterior surface with an outside diameter which forms a close sliding fit within the supply line after the step of disconnecting;

connecting the supply line to the source of cleaning fluid, thus propelling the first termination piston through the supply line by means of the cleaning fluid so as to cause the termination piston to wipe paint off the interior walls of the supply line by virtue of the termination piston being propelled through the supply line and so as to cause the cleaning fluid to clean the interior walls of the supply line;

inserting a second termination piston after a predetermined amount of cleaning fluid has entered the supply line;

propelling the second termination piston through the supply line until essentially no paint of the first color remains in the supply line;

connecting the supply line to the second source of paint so as to fill the supply line with the second color paint to allow said applicator means to again paint an article with the second paint color; and

removing the first and second termination pistons from the supply line.