Patent Publication Number: US-2011076411-A1

Title: Fluid supply device for spraying system

Description:
The present invention relates to a fluid supply for a sprayer, particularly for a paint or varnish sprayer, and a method of its use. 
     For a paint change in a sprayer, the system must be cleaned of the paint used, and subsequently, the new paint has to be put into use. To this end, when the pumps are on the outside, the feed lines to the atomizer and all the parts contained in them, such as paint changer, pressure regulator, or metering units, are cleaned with a cleaning fluid. In these methods, the paint contained in the line is discarded, which entails a high consumption of paint and cleaning fluid and a long flushing time. 
     Another method of cleaning feed lines is feeding the paint back into a ring line and then cleaning the feed lines with cleaning fluid. In these methods, it is true that the loss of paint when changing paints can be kept low, but the technical effort for control is very great, making such systems very liable to break down, and cost-intensive. 
     Proceeding from this state of the art and the disadvantages described in this connection, the object to be attained was therefore providing a sprayer that allows a rapid and efficient paint change, and, in this connection, makes do without a pigging system for the cleaning required for this. Furthermore, such a system should be characterized by low installation effort and cost. 
     According to the invention, this object is attained in that a fluid supply for a sprayer, particularly a paint or varnish sprayer, is composed of two modules. 
     The first module of the device according to the invention consists of: 
     at least two ring or supply lines for paint or varnish that are independent of one another and connected with the first paint changer provided with paint valves and circulation valves, 
     at least two lines for circulating respective paints or varnishes, that are independent of one another, and that extend from the first paint changer to a second paint changer provided with release valves, 
     where on the one hand the paint valves of the first paint changer are connected with a cleaning-agent valve and an air valve, by a common line, and on the other hand are connected with the release valves, a drain valve, as well as a drain line of the second paint changer, through a common pressure regulation line, through a pressure regulator and a metering pump. 
     The second module comprises at least two lines that are independent of one another for feeding the paints or varnishes from a second paint changer to a third paint changer and/or a two-component mixer, where the third paint changer and/or the two-component mixer has release valves and/or return lines for paints and varnishes, and is preferably provided in the immediate vicinity of the spraying device. 
     Such a system allows rapid and efficient automatic paint change, with the valve arrangement according to the invention allowing a low installation effort and cost for operation, and, in particular, for the cleaning that is required. Furthermore, no complicated pigging systems are used. 
     In the second module, the fluid supply according to the invention can optionally be equipped with any desired number of paint changers and/or two-component mixers. Fluids in the sense of the present invention are all fluids that can be used for surface treatment, particularly paints or varnishes. The device according to the invention thus makes it possible to transport a plurality of paints or varnishes, for example 20 or 30 paints or varnishes, separately from one another in the fluid supply. Cleaning fluid in the sense of the invention is understood to mean suitable solvents that can completely remove the paints and varnishes, in each instance. If a two-component mixer is present in the second module, it is advantageous to provide this module with a feed line for a hardener, the metering of the hardener being done by a valve referred to below as a hardener valve. Thus, it is possible to mix a hardener with the paint and/or varnish mixture. It is furthermore advantageous if the paint changer has circulation valves. It is advantageous if needle valves are used for the circulation valves, paint valves, and hardener valves, where the needle valves can be turn on and off pneumatically, through control lines. It is advantageous if the control takes place in computer-based manner, for example through a PLC system. In an advantageous embodiment of the fluid supply, the metering pump in the first module is connected with a cleaning agent line through a separate flushing valve; thus, this metering pump can be flushed with a cleaning agent, independently of the remaining system, where it is particularly advantageous if the metering pump is a flushable metering gear pump. In another advantageous embodiment, the first module is mounted outside of a cabin or on a cabin wall, and the second module is mounted on a robot or automatic varnishing machine. 
     A method according to the invention, for supplying fluid to a sprayer, particularly to a paint or varnish sprayer, is presented below: 
     In this connection, paints or varnishes are passed into the first paint changer provided with the paint valves and circulation valves, through at least two supply lines that are independent of one another. These paints or varnishes can be passed to a second paint changer provided with release valves through at least two separate lines for circulating the paints or varnishes. Furthermore, the paints or varnishes are passed from the second paint changer to a third paint changer and/or to a two-component mixer provided in a second module, through at least two lines, which are independent of one another. If it is practical, fundamentally two or more paint changers and/or two-component mixers as well as any desired combinations of these can also be provided in the second module. The paints can therefore constantly circulate through the system, in separate circuits, or can be optionally passed from the third paint changer and/or from the two-component mixer to a spraying device, when the valves are switched accordingly. In the cleaning mode, air and/or a fluid cleaning agent is/are passed through the first paint changer, through a common line with the pressure regulator, and a metering pump, through the second paint changer, through a drain valve, into a drain line. Furthermore, at the same time, air and/or a fluid cleaning agent is/are passed through the third paint changer and/or the two-component mixer and the spraying device. It is particularly practical for cleaning purposes to alternately pulse fluid cleaning agent and air through these components, with the shape of the pulse adapted to the fluid to be removed. If necessary, cleaning can also take place exclusively with a fluid cleaning agent, without air. 
     The fluid supply according to the invention furthermore has the advantages that in spite of the fact that the metering pump is outside, the paints circulate through the complete device, and circulation can be started or stopped. Furthermore, it is advantageous that a very slight loss of paint and cleaning agent occurs, that a rapid paint change is possible in spite of the pumps being outside, that there is simple and rapid access to all the components, and that the effort for the technology and the control structure is very low, as compared with a pigging system. 
     The fluid supply for a sprayer, according to the invention, can be used to coat a surface with a varnish, for example, preferably in a varnish coating system. 
    
    
     
       An illustrated embodiment of the invention is shown in the drawings and will be described in greater detail in the following. The drawing shows: 
         FIG. 1  is a media plan for a two-paint fluid supply having a two-component mixer that is mounted on a robot or an automatic varnishing machine, 
         FIG. 2   a, b  a paint changer having circulation valves, 
         FIG. 3   a, b  a two-component mixer having circulation valves, and 
         FIG. 4  a media plan for a fluid supply with two paints, having a paint changer that is mounted on a robot or an automatic varnishing machine. 
     
    
    
       FIG. 1  shows a fluid supply for a paint sprayer  40  for two paints, as an example. In this connection, the device consists of two modules  1  and  2 , the first module  1  being mounted in a cabin wall, and the second module  2  being mounted on a robot or automatic varnishing machine. The two paints are passed into the first module  1  through two supply lines  50  and  60  for paints, which lines are independent of one another, and extend through paint valves  103  and  104  provided in the first paint changer  100 , and to circulation valves  105  and  106  also in the first paint changer  100 . Lines  51  and  61  for circulating the paints are connected to outputs of these circulation valves  105  and  106 . These lines end at respective paint valves  401  and  402  of the second paint changer  400 . The paints also can pass through these paint valves  401  and  402  and can then through release valves  501  and  503  provided in a two-component mixer  510  of the second module  1 , through connected lines  52  and  62 . The paints can then be passed back to the corresponding paint reservoirs, not shown in the drawing, through circulation valves  502 ,  504  and return lines  53  and  63  connected with them. Thus, the paints can circulate through the entire system. 
     In the two-component mixer  510  of the second module  2 , as can also be seen in  FIG. 1 , the release valves  501  and  503  are connected through a short line  81  with a mixer  76  to which an atomizer  77  for applying paints to surfaces is connected. Furthermore,  FIG. 1  shows how a hardener can be fed to the mixer  76  by a release valve  505  provided in the two-component mixer  510 . In this connection, the hardener is moved through a line  75  and a pump, not shown in the drawing, and passed to the mixer  76  through a line  80 . According to  FIG. 1 , two respective air-flush valves  508  and  509  and respective two cleaning-agent valves  506 ,  507  are furthermore built into the two-component mixer  510 , which valves can be appropriately supplied with air and cleaning agent through feed lines  73  and  74 . 
     All the valves in this embodiment shown in  FIG. 1  are pneumatically turned on and/or off via control lines  78 . In this connection, the control lines  78  shown always schematically indicate the all the individual control lines, since all the valves can be controlled separately. 
     As is furthermore evident from  FIG. 1 , the paint valves  103  and  104  in the first paint changer  100  are connected with a cleaning-agent valve  101  and an air valve  102  through a line  82 , these valves being appropriately supplied with pulsed air and cleaning agent through the lines  70  and  71 . Furthermore, a common line  55   a  leads from the paint valves  103  and  104  to a 6 ccm metering pump  300  through a pressure regulator  200 . The metering pump  300  is furthermore connected with the release valves  401  and  402  of the second paint changer by a line  55   b  and is connected with a drain line  56  through a drain valve  403 . 
     According to  FIG. 1 , the metering pump  300  is made as a flushable metering gear pump. This pump can be flushed with a cleaning agent through a flushing valve  301  and a separate line  79 . 
       FIGS. 2   a  and  2   b  show the paint changer  100  for two paints, with its flow-through paint valves  103  and  104 , the circulation valves  105  and  106 , as well as the cleaning-agent valve  101  and the air valve  102 . The common paint line  82  runs inside the paint changer  100 . In this connection, the valves are needle valves and are screwed into the paint changer  100 , thereby allowing easy replacement, if necessary. 
       FIGS. 3   a  and  3   b  show a two-component mixer  510  for two paints and a hardener, having the release valves  501  and  503  for the paints, and a release valve  505  for the hardener. The circulation valves  502  and  504 , the cleaning-agent valves  506  and  507 , and the air valves  508  and  509  are also screwed in. The paint line  81  and the hardener line  80  run inside the two-component mixer  510 . In this connection, the valves are also needle valves. 
       FIG. 4  schematically shows a media plan for a fluid supply with two paints and having a paint changer  500 , which is mounted on a robot or automatic varnishing machine. In this connection, the module  1  has the same construction as the device described under  FIG. 1 . Thus, the module  1  also contains a paint changer  100 , a pressure regulator  200 , a metering pump  300 , and a second paint changer  400 . In this illustrated embodiment, the lines  52  and  62  that lead away from the second paint changer  400  are passed through the release valves  501  and  503  provided in the paint changer  50  of the second module  2 . The paints can then be returned to the corresponding paint reservoirs, not shown in the drawing, through circulation valves  502  and  504 , and return lines  53  and  63  connected with them. 
     In the paint changer  500  of the second module  2 , the release valves  501  and  503  are connected with an atomizer  77 , through a short line  83 , as can also be seen in  FIG. 4 . 
     According to  FIG. 4 , an air-flush valve  508  and a cleaning-agent valve  506  are furthermore built into the paint changer  500  and are supplied with air and cleaning agent through the respective feed lines  73  and  74 . All the valves in this illustrated embodiment shown in  FIG. 4  are also turned on and/or off pneumatically, through control lines  78 . 
     In the following, it is described how fluid is supplied to a sprayer  40  according to the invention, having a two-component mixer  510  that is mounted on a robot or automatic varnishing machine. To this end, circulation of the two paints takes place, using a system according to  FIG. 1 , in that these paints are drawn from unillustrated reservoirs, pass through the closed paint valves  103  and  104 , through the supply lines  50  and  60 , and then through the open circulation valves  105  and  106  into the respective lines  51  and  61 . The paints are then drawn from these lines through the closed paint valves  401  and  402 , and also drawn through the closed paint valves  501 ,  502  through the lines  52  and  62 . Circulation of the paints through the system is made complete with the return of the paints through the open circulation valves  502  and  504  and the lines  53  and  63 . In a next switching possibility of the valves, a paint is supplied. To this end, a paint  1 , for example, is pumped into a drain line  56 , through the line  50 , through the paint valve  103  that is now open, through the lines  82  and  55   a,  through the metering pump  300 , through the line  55   b,  through the open drain valve  403  while the circulation valves  106  and  502  for the paint  1  are closed. Thus, the circulation of the paint  1  to the two-component mixer  510 , through the second paint changer  400 , is interrupted. While the paint is being supplied, the bypass valve  302  at the metering pump  300  is open, so that the paint can quickly be passed into the drain line  56 , and is not limited, in terms of its flow, by the passage of the metering pump  300 . When the section between the paint valve  103  all the way to the drain line  56  has been completely filled with paint  1 , the drain valve  403  is closed. Subsequently, the paint valve  401  and the paint valve  501  can be opened at the same time, and the bypass valve  302  can be closed. Now, the paint  1  is metered into the mixer  76  through the metering pump  300 , so that the paint exits from the atomizer  77 . In this connection, charging of the paint takes place very rapidly, since only the section between the metering pump  300  and the pistol of the atomizer  77  has to be pressed down. When the paint is changed, the paint valves  103 ,  501  are closed, and the circulation valves  106  and  502  are opened so that the paint  1  is back in circulation mode again. For cleaning, air and a solvent are simply alternately flushed out of the drain valve  403 , from the first paint changer  100 , through the pressure regulator  200 , and through the metering pump  300 . Since this section is very short, cleaning can take place in a very short time and with a low consumption of solvent. At the same time, the section from the two-component mixer  510  all the way to the atomizer  77  is cleaned. Since this section is also very short, here again, cleaning can take place in a very short time and with a low consumption of solvent. 
     A fluid supply according to the sprayer shown in  FIG. 4 , having a paint changer  500  that is mounted on a robot or automatic varnishing machine, is operated in a manner analogous to the system shown in  FIG. 1 . 
     REFERENCE SYMBOL LIST 
     
         
           1  first module 
           2  second module 
           40  paint sprayer 
           50  line for paint or varnish  1 , supply 
           51  line for paint or varnish  1 , circulation 
           52  line for paint or varnish  1 , to the third paint changer or two-component mixer 
           53  line for paint or varnish  1 , return 
           55   a  pressure regulator line, ahead of the metering pump 
           55   b  pressure regulator line, behind the metering pump 
           56  drain line 
           60  line for paint or varnish  2 , supply 
           61  line for paint or varnish  2 , circulation 
           62  line for paint or varnish  2 , to the third paint changer or two-component mixer 
           63  line for paint or varnish  2 , return 
           70  feed line, pulsed air 
           71  feed line, cleaning agent 
           73  feed line to robot or automatic varnishing machine, air 
           74  feed line to robot or automatic varnishing machine, cleaning agent 
           75  feed line, hardener 
           76  mixer element 
           77  spraying device or atomizer 
           78  control lines 
           79  cleaning agent line, metering pump 
           80  hardener line, in the two-component mixer 
           81  paint line, in the two-component mixer 
           82  paint line, in the first paint changer 
           83  paint line, in the third paint changer 
           100  first paint changer 
           101  cleaning-agent valve 
           102  air valve 
           103  paint valve, paint or varnish  1   
           104  paint valve, paint or varnish  2   
           105  circulation valve, paint or varnish  1   
           106  circulation valve, paint or varnish  2   
           200  pressure regulator 
           300  metering pump or metering gear pump, flushable 
           301  flushing valve for metering pump 
           302  bypass valve for metering pump 
           400  second paint changer 
           401  release valve, paint or varnish  1   
           402  release valve, paint or varnish  2   
           403  drain valve 
           500  third paint changer 
           501  release valve, paint or varnish  1   
           502  circulation valve, paint or varnish  1   
           503  release valve, paint or varnish  2   
           504  circulation valve, paint or varnish  2   
           505  release valve, hardener 
           506  cleaning-agent valve 
           507  cleaning-agent valve 
           508  air-flush valve 
           509  air-flush valve 
           510  two-component mixer