Installation and method for coating objects

Abstract

An installation for coating objects, in particular vehicle wheels, has a dipping trough which is filled with a coating liquid into which the objects can be dipped. In order to reduce the complexity of the piping, there is provided a combined recirculation and filtration circuit for recirculating and filtering the coating liquid, wherein the recirculation and filtration circuit includes a pump, at least one recirculation outlet, arranged in the dipping trough, for the coating liquid, and a filtration device having a residue connection and a filtrate connection, wherein the residue connection is connected to the at least one recirculation outlet in the dipping trough.

What is claimed is: 
     
         1 . A method for coating objects, comprising the steps of:
 a) immersing objects in a dip tank which is filled with a coating fluid,   b) circulating and filtering the coating fluid in the dip tank by
 removing at least a portion of the coating fluid from the dip tank; 
 filtering the coating fluid which has been removed from the dip tank in a filtration device having a retentate connection and a filtrate connection, whereby retentate and filtrate are separated in the filtering device and the retentate accumulates at the retentate connection and the filtrate accumulates at the filtrate connection; 
 connecting the retentate connection to all of one or more circulation outlets arranged in the dip tank; 
 returning the retentate to the dip tank through all of the one or more circulation outlets arranged in the dip tank; and 
 generating a circulation flow within the coating fluid in the dip tank by returning the retentate to the dip tank from the retentate connection through the one or more circulation outlets. 
   
     
     
         2 . The method of  claim 1 , wherein the coating fluid is maintained in a homogenous state by the circulation flow formed by the returning of retentate and circulating of the coating fluid by the one or more circulation outlets. 
     
     
         3 . The method of  claim 1 , further comprising the step of connecting the filtrate connection to a cleaning tank to provide the filtrate to the cleaning tank, the objects being cleaned in the cleaning tank after being immersed in the dip tank. 
     
     
         4 . The method of  claim 1 , further comprising the step of controlling the temperature of the portion of the coating fluid removed from the dip tank. 
     
     
         5 . The method of  claim 1 , further comprising the steps of:
 surrounding one or more electrodes used to generate a voltage in the dip tank with one or more exchange diaphragms, and   providing dialysis fluid to the dip tank in order to reduce the acid content of the coating fluid in the dip tank.   
     
     
         6 . The method of  claim 1 , wherein the portion of the coating fluid removed from the dip tank is removed by overflowing from the dip tank into an overflow tank, wherein the coating fluid which overflows into the overflow tank is pumped from the overflow tank to the filtration device. 
     
     
         7 . The method of  claim 1 , further comprising the step of pre-filtering the portion of the coating fluid removed from the dip tank, wherein the coating fluid is separated into the retentate and the filtrated in an ultra-filtration module after being pre-filtered. 
     
     
         8 . The method of  claim 1 , wherein the one or more circulation outlets each comprise an injector nozzle. 
     
     
         9 . The method of  claim 1 , wherein the objects are vehicle wheels. 
     
     
         10 . A method for coating objects, comprising the steps of:
 a) immersing objects in a dip tank which is filled with a coating fluid,   b) circulating and filtering the coating fluid in the dip tank by
 removing at least a portion of the coating fluid from the dip tank; 
 separating retentate and filtrate from the portion of the coating fluid removed from the dip tank; 
 accumulating the retentate at a retentate connection; 
 connecting the retentate connection to all of one or more circulation outlets arranged in the dip tank; 
 returning the retentate to the dip tank through all of the one or more circulation outlets arranged in the dip tank; and 
 generating a circulation flow within the coating fluid in the dip tank by returning the retentate to the dip tank from the retentate connection through the one or more circulation outlets. 
   
     
     
         11 . The method of  claim 10 , wherein the coating fluid is maintained in a homogenous state by the circulation flow formed by the returning of retentate and circulating of the coating fluid by the one or more circulation outlets. 
     
     
         12 . The method of  claim 10 , further comprising the steps of:
 accumulating filtrate at a filtrate connection; and   connecting the filtrate connection to a cleaning tank to provide the filtrate to the cleaning tank, the objects being cleaned in the cleaning tank after being immersed in the dip tank.   
     
     
         13 . The method of  claim 10 , further comprising the step of controlling the temperature of the portion of the coating fluid removed from the dip tank. 
     
     
         14 . The method of  claim 10 , further comprising the steps of:
 surrounding one or more electrodes used to generate a voltage in the dip tank with one or more exchange diaphragms, and   providing dialysis fluid to the dip tank in order to reduce the acid content of the coating fluid in the dip tank.   
     
     
         15 . The method of  claim 10 , wherein the portion of the coating fluid removed from the dip tank is removed by overflowing from the dip tank into an overflow tank, wherein the coating fluid which overflows into the overflow tank is pumped from the overflow tank to the filtration device. 
     
     
         16 . The method of  claim 10 , wherein the one or more circulation outlets each comprise an injector nozzle. 
     
     
         17 . An installation for coating objects comprising:
 a) a dip tank which is filled with a coating fluid in which objects can be dipped, wherein   b) a filtration device for filtering at least a portion of the coating fluid which is removed from the dip tank, wherein the filtration device comprises
 a pump having a pump inlet and a pump outlet, wherein the pump inlet is at least indirectly connected to the dip tank, 
 a retentate connection where retentate is accumulated, 
 a filtrate connection where filtrate is accumulated 
   c) one or more circulation outlets arranged in the dip tank for the coating fluid, wherein the retentate connection is connected to all of the one or more circulation outlets in the dip tank and the retentate is returned to the dip tank from the retentate connection through all of the one or more circulation outlets.   
     
     
         18 . The installation according to  claim 17 , wherein the one or more circulation outlets each comprise an injector nozzle, wherein the one or more circulation outlets and injector nozzles generate a circulation flow in the dip tank, the circulation flow maintaining the coating fluid in the dip tank in a homogenous state. 
     
     
         19 . The installation according to  claim 17 , further comprising a heat exchanger, the heat exchanger controlling the temperature of the portion of the coating fluid removed from the dip tank. 
     
     
         20 . The installation according to  claim 17 , wherein the filtrate connection of the filtration device is at least indirectly connected to a cleaning tank, in which the objects are cleaned after the coating operation, the filtrate being provided to the cleaning tank.