AUTOMATIC CONTROL METHOD AND APPARATUS FOR CONCENTRATION OF FLUORIDE IN PLATING BATH FOR ELECTROLYTIC CHROMIC ACID TREATED STEEL PLATE

摘要

PURPOSE:To achieve the automatic control of a plating bath by a simple method by measuring the potential of a sample with an ion electrode after the addition of a chemical agent thereto to determine the concentration of all fluorine ions and the concentration of active fluorine ions based on a calibration curve prepared. CONSTITUTION:A sample is taken into a measuring tank 8 with a pump 17 from a plating bath tank 12 and a buffer is injected into the tank 8 with a pump 19 from a tank 4. After they are mixed thoroughly, potential is measured with an ion electrode 1 and a conversion assay of the concentration of all fluorine ions is performed with a microcomputer 9. Then, a NaCl solution is fed to an assayed sample solution, sampled into a measuring tank 8' with the pump 17, from a tank 6 with a pump 20 and after they are mixed thoroughly, potential is measured with an ion electrode 2 and a conversion assay of the concentration of active fluorine ions is performed with the microcomputer 9. The measured concentrations of both the fluorides are compared with a preset target concentration and addition values of both the fluorides are calculated. Based on the results, they are fed to a plating bath tank 12 by a specified amount from chemical liquid tanks 10 and 11.