Electrodeposition painting method and throughflow system for carrying out said method

Abstract

Method of electrocoating substrates using an electrocoating tank, wherein the substrates are connected as cathode or anode.

1 . A method of electrocoating electrically conductive three-dimensional substrates ( 2 ) in a continuous installation ( 1 ) comprising 
 supplying an electrocoating tank ( 1 . 1 ) with electrocoat material,    wherein said electrocoating tank comprises an overflow tank ( 1 . 2 ) for receiving electrocoat material,    at least one circulating pump ( 1 . 3 ) for drawing off the electrocoat material on the base ( 1 . 4 ) of the overflow tank ( 1 . 2 ),    at least one circulating pump ( 1 . 5 ) for drawing off the electrocoat material on the tank base ( 1 . 6 ) at the end ( 1 . 7 ) of the electrocoating tank ( 1 . 1 ) that is opposite the overflow tank ( 1 . 2 ),    at least two flood pipes ( 1 . 8 ) for returning the electrocoat material drawn off by way of the circulating pumps ( 1 . 3 ) and ( 1 . 5 ) to the electrocoating tank ( 1 . 1 ) at its base ( 1 . 6 ) in such a way that in the electrocoating tank ( 1 . 1 ) in the longitudinal direction a directed tank flow ( 1 . 9 ) is produced and maintained,    the tank flow ( 1 . 9 ) in the area of the tank base ( 1 . 6 ) being opposite to the tank flow ( 1 . 9 ) in the area of the bath surface ( 1 . 10 ), and    at least one conveying device ( 1 . 11 ) with means of transporting the substrates ( 2 ) to the electrocoating tank ( 1 . 1 ),    rotating and immersing the substrates ( 2 ) in the electrocoating tank ( 1 . 1 ) at one end thereof in the immersing area ( 1 . 12 ),    transporting the substrates ( 2 ) through the electrocoating tank ( 1 . 1 ) in the longitudinal direction, and rotating and emersing the substrates from the electrocoating tank ( 1 . 1 ) at its other end, as viewed in the transport direction, in the emersing area ( 1 . 13 ),    wherein the substrates ( 2 )    I. are connected as cathode or anode and    II. with the aid of the conveying device or devices ( 1 . 11 ) 
   11 .1 are supplied over the overflow tank ( 1 . 2 ) to the immersing area ( 1 . 12 ) of the electrocoating tank ( 1 . 1 ),  
   11 .2 on immersion in the electrocoating tank ( 1 . 1 ) are rotated about a horizontal axis perpendicular to the transport direction at an angle of >100° to the original position,  
   11 .3 are passed in the new orientation through the electrocoating tank ( 1 . 1 ) and coated,  
   11 .4 on emersion from the electrocoating tank ( 1 . 1 ) are rotated in the emersing area ( 1 . 13 ) about a horizontal axis perpendicular to the transport direction back into the original position, and  
   11 .5 following emersion are passed on for further processing,  
   which comprises    drawing off the electrocoat material by way of the circulating pumps ( 1 . 3 ) and ( 1 . 5 ) being returned by way of the flood pipes ( 1 . 8 ) to the base ( 1 . 6 ) of the electrocoating tank ( 1 . 1 ) in such a way as to produce and maintain a directed tank flow ( 1 . 9 ) which flows in the transport direction of the substrates ( 2 ) in the area of the tank base ( 1 . 6 ) and opposite to the transport direction of the substrates ( 2 ) in the area of the bath surface ( 1 . 10 ).    
   
   
       2 . The method as claimed in  claim 1 , wherein the substrates ( 2 ) have cavities.  
   
   
       3 . The method as claimed in  claim 1 , wherein the substrates ( 2 ) are rotated in the transport direction.  
   
   
       4 . The method as claimed in  claim 1 , wherein the substrates ( 2 ) are vehicle bodies, radiators or casings of washing machines, dishwashers or ovens.  
   
   
       5 . The method as claimed in  claim 1 , wherein the substrates ( 2 ) are oriented transverse to the axis of rotation or longitudinally to the axis of rotation.  
   
   
       6 . The method as claimed in  claim 1 , wherein on immersion in the electrocoating tank ( 1 . 1 ) the substrates ( 2 ) are rotated in the transport direction at an angle of about 180° or 180° to the original position.  
   
   
       7 . The method as claimed in  claim 1 , wherein on transport through the electrocoating tank the substrates ( 2 ) are moved.  
   
   
       8 . The method as claimed in  claim 1 , wherein the substrates ( 2 ) are connected as cathode.  
   
   
       9 . The method as claimed in  claim 8 , wherein the electrocoat material is a cathodically depositable electrocoat material.  
   
   
       10 . The method as claimed in  claim 1 , wherein the electrocoat material is drawn off by means of the circulating pumps ( 1 . 3 ) and ( 1 . 5 ) is filtered ( 1 . 14 ) before being returned to the electrocoating tank ( 1 . 1 ).  
   
   
       11 . The method as claimed in  claim 10 , wherein the electrocoat material drawn off is subjected to ultrafiltration.  
   
   
       12 . The method as claimed in  claim 1 , wherein the continuous installation ( 1 ) comprises at least one power supply, electronic, mechanical, and pneumatic measurement and control devices, electric motors, overflow devices, heat exchangers, devices for the supply of electrocoat material, electrocoat material components, and neutralizing agents, ultrafiltration units, filters, anolyte circuits for the cathodically depositable electrocoat material, and rinsing zones.  
   
   
       13 . A continuous installation ( 1 ) for implementing the method as claimed in any of  claims 1  to  12 , comprising 
 an electrocoating tank ( 1 . 1 ) containing the electrocoat material,    an overflow tank ( 1 . 2 ) containing the electrocoat material,    at least one circulating pump ( 1 . 3 ) for drawing off the electrocoat material on the base ( 1 . 4 ) of the overflow tank ( 1 . 2 ),    at least one circulating pump ( 1 . 5 ) for drawing off the electrocoat material on the tank base ( 1 . 6 ) at the end ( 1 . 7 ) of the electrocoating tank ( 1 . 1 ) that is opposite the overflow tank ( 1 . 2 ),    at least two flood pipes ( 1 . 8 ) for returning the electrocoat material drawn off by way of the circulating pumps ( 1 . 3 ) and ( 1 . 5 ) to the electrocoating tank ( 1 .  1 ) at its base ( 1 . 6 ) in such a way that in the electrocoating tank ( 1 . 1 ) in the longitudinal direction a directed tank flow ( 1 . 9 ) is produced,    the tank flow ( 1 . 9 ) in the area of the tank base ( 1 . 6 ) being opposite to the tank flow ( 1 . 9 ) in the area of the bath surface ( 1 . 10 ),    at least one conveying device ( 1 . 11 ) with means of transporting the substrates ( 2 ) to the electrocoating tank ( 1 . 1 ), rotating and immersing the substrates ( 2 ) in the electrocoating tank ( 1 . 1 ) at one end thereof in the immersing area ( 1 . 12 ), transporting the substrates ( 2 ) through the electrocoating tank ( 1 . 1 ) in the longitudinal direction, and rotating and emersing the substrates from the electrocoating tank ( 1 . 1 ) at its other end in the emersing area ( 1 . 13 ),    an immersing area ( 1 . 12 ) at the end of the electrocoating tank ( 1 . 1 ), to which the overflow tank ( 1 . 2 ) connects, and    an emersing area ( 1 . 13 ) at the other end of the electrocoating tank ( 1 . 1 ) as viewed in the transport direction of the substrates,    wherein the directed tank flow ( 1 . 9 ) in the area of the bath surface ( 1 . 10 ) is opposite to the transport direction of the substrates ( 2 ).    
   
   
       14 . The continuous installation ( 1 ) as claimed in  claim 13 , which comprises at least one power supply, electronic, mechanical, and pneumatic measurement and control devices, electric motors, pumps, overflow devices, heat exchangers, devices for the supply of electrocoat material, electrocoat material components, and neutralizing agents, ultrafiltration units, filters, anolyte circuits for the cathodically depositable electrocoat material, and rinsing zones.