Method and apparatus for controlling concentration of electrolytic solution

Abstract

In the electrolytic treatment, an acid concentration meter measures the concentration of hydrochloric acid. The difference from a measured value PV b to a preset value SV b of the concentration of hydrychloric acid is larger than preset value e, hydrochloric acid is fed out from an acid feeding section. The aluminum concentration meter measures the concentration of the aluminum chloride. A water feed cycle is calculated from a measured value PV a and a preset value SV a of the concentration of hydrochloric acid, and a total value of the electrolytic current I generated by a power source section. At every water feed cycle, a water feeding section feeds water to add to the electrolytic solution.

What is claimed is:  
     
         1 . A method for controlling a concentration of an electrolytic solution for making an electrolytic treatment of a metallic material, comprising steps of: 
 measuring a acid concentration of acid in said electrolytic solution;    measuring a salt concentration of salt which is generated by ionizing part of said metallic material in said electrolytic solution in said electrolytic treatment; and    adding at least one of a diluting liquid and a fresh acid according to said measured acid concentration, said measured salt concentration, and a current value of said electrolytic current supplied during said electrolytic treatment.    
     
     
         2 . A method as claimed in  claim 1 , further comprising a step of calculating a feed cycle of adding a predetermined amount of said diluting liquid from said measured salt concentration and said current value.  
     
     
         3 . A method as claimed in  claim 2 , further comprising steps of: 
 calculating a difference from said measured acid concentration to an objected acid concentration; and    adding said fresh acid to said electrolytic solution when said difference is larger than a predetermined limit value.    
     
     
         4 . A method as claimed in  claim 2 , wherein when said current value is I, and A and B are optional constants, a standard cycle T o  for adding said diluting liquid to said electrolytic solution is T o =A/I+B, 
 and wherein when said measured salt concentration is PV a , said objected salt concentration is SV a , and C and D are optional constants, said feed cycle T for adding the predetermined amount of said diluting liquid is,      T=T   o ×(1 +C ×( PV   a   −SV   a ))+ D.      
     
     
         5 . A method as claimed in  claim 4 , wherein said metallic material is an aluminum plate used for a substrate of a PS plate.  
     
     
         6 . A method as claimed in  claim 5 , wherein said acid is hydrochloric acid.  
     
     
         7 . An apparatus for controlling a concentration of an electrolytic solution in which an electrolytic treatment of a metallic material is made, comprising: 
 an acid concentration meter for measuring an acid concentration of acid contained in said electrolytic solution;    a salt concentration meter for measuring a salt concentration of salt which is generated by ionizing part of said metallic material in said electrolytic treatment;    a current meter for measuring a current value of said electrolytic current supplied during said electrolytic treatment;    an acid concentration controller for controlling said acid concentration, said acid concentration controller adding a fresh acid to said electrolytic solution on the basis of a measured acid concentration and an objected acid concentration; and    a salt concentration controller for controlling said salt concentration of said metallic salt, said salt concentration controller calculating a controlling period of said salt concentration on the basis of a measured salt concentration and said current value, to add a diluting liquid to said electrolytic solution at each controlling period.    
     
     
         8 . An apparatus as claimed in  claim 7 , wherein when said current value is I, and A and B are optional constants, a standard cycle T o  for adding said diluting liquid to said electrolytic solution is T o =A/I+B, 
 and wherein when said measured salt concentration is PV a , said objected salt concentration is SV a , and C and D are optional constants, said feed cycle T for feeding said diluting liquid is,      T=T   o ×(1 +C ×( PV   a   −SV   a ))+ D.