System and method for controlling electrodeposition coating

Abstract

An exemplary system for controlling electrodeposition coating for electrochemically forming a coating film on a coating object in an electrodeposition tank storing electrodeposition solution includes, a positive electrode configured to apply a positive electrode voltage to a positive electrode disposed in the electrodeposition tank, a negative electrode configured to apply a negative electrode voltage to the coating object transferred by a hanger, and an electrodeposition controller configured to electrochemically deposit the coating film on an external surface and an internal surface of the coating object by applying the positive electrode voltage to the positive electrode and the negative electrode voltage to the negative electrode, where the electrodeposition controller may be configured to control voltage, current, and pulse in multi-stages over time from a dip-in time point to a draw-out time point of the coating object into and from the electrodeposition tank.

1 . A system for controlling electrodeposition coating for electrochemically forming a coating film on a coating object in an electrodeposition tank storing electrodeposition solution, the system comprising:
 a positive electrode configured to apply a positive electrode voltage to a positive electrode disposed in the electrodeposition tank;   a negative electrode configured to apply a negative electrode voltage to the coating object transferred by a hanger; and   an electrodeposition controller configured to electrochemically deposit the coating film on an external surface and an internal surface of the coating object by applying the positive electrode voltage to the positive electrode and the negative electrode voltage to the negative electrode;   wherein the electrodeposition controller is configured to control voltage, current, and pulse in multi-stages over time from a dip-in time point to a draw-out time point of the coating object into and from the electrodeposition tank.   
     
     
         2 . The system of  claim 1 , wherein the electrodeposition controller is configured to adjust the voltage, current, and pulse over time in three stages. 
     
     
         3 . The system of  claim 2 , wherein the electrodeposition controller is configured to set a limit value of an applied voltage such that the applied voltage does not exceed the limit value. 
     
     
         4 . The system of  claim 1 , wherein the electrodeposition controller is configured to increase a current density through a pulse control of the current to increase a throwpower for coating film thickness formation of the internal surface. 
     
     
         5 . The system of  claim 4 , wherein the electrodeposition controller comprises:
 a first stage rectifier, a second stage rectifier, and a third stage rectifier for controlling multi-stages of voltage, current, and pulse; and   a controller configured to control the voltage, current, and pulse over time through a control program.   
     
     
         6 . The system of  claim 5 , wherein the controller is configured to identify a position of the coating object through on/off signals of a first limit switch and a second limit switch, and selectively control a corresponding rectifier. 
     
     
         7 . The system of  claim 5 , wherein the control program comprises a display comprising:
 a charge amount display portion configured to display a total charge amount over time during electrodeposition;   a voltage display portion configured to display the voltage over time;   a current display portion configured to display the current over time; and   a user interface configured to display a control condition setting screen for setting the current, voltage, pulse, and duty ratio according to the time.   
     
     
         8 . The system of  claim 7 , wherein the controller is configured to differently set the current, voltage, pulse, and duty ratio through the user interface depending on the coating object. 
     
     
         9 . The system of  claim 7 , wherein the controller is configured to control the pulse of the current in a range of 5 kHz to 10 kHz. 
     
     
         10 . The system of  claim 9 , wherein the controller is configured to set a duty ratio of the pulse to above 50% 
     
     
         11 . A method for controlling electrodeposition coating for electrochemically form a coating film on a coating object dipped in an electrodeposition tank storing an electrodeposition solution, the method comprising:
 recognizing the coating object entering an electrodeposition area and setting a preset voltage, current, and pulse in a multi-stage control condition depending on the coating object;   performing a first stage control while a first limit switch is turned on by dipping in of the coating object into the electrodeposition tank;   performing a second stage control with an increased voltage and current compared to the first stage control when a second limit switch is turned on due to movement of the coating object; and   performing a third stage control with a further increased voltage and current after finishing the second stage control, at a time when a preset period has lapsed since the second stage control is initiated or at a time when a third limit switch is turned on due to movement of the coating object.   
     
     
         12 . The method of  claim 11 , wherein, in the performing the third stage control, the voltage is limited to not exceed a preset limit value. 
     
     
         13 . The method of  claim 11 , wherein the performing the third stage control comprises increasing a current density through a pulse control of the current to increase a throwpower for coating film thickness formation of the internal surface. 
     
     
         14 . The method of  claim 13 , wherein the performing the third stage control comprises controlling the pulse of the current in a range of 5 kHz to 10 kHz. 
     
     
         15 . The method of  claim 14 , wherein the performing the third stage control comprises setting a duty ratio of the pulse to be above 50%. 
     
     
         16 . The method of  claim 11 , wherein a pause period is interposed after the performing the second stage control and before the performing the third stage control. 
     
     
         17 . The method of  claim 11 , further comprising, after the performing the third stage control, limiting the voltage under a limit value while controlling the current to be unlimited.