Electrochemical polishing of non-uniform features

Patent metadata

Field	Value
Publication number	US-2017355032-A1
Application number	US-201715598666-A
Country	US
Kind code	A1
Filing date	May 18, 2017
Priority date	Jun 9, 2016
Publication date	Dec 14, 2017
Grant date	—

Abstract

A method of controlling a working gap between one or more cathodic tools and an anodic workpiece in an electrochemical material dissolution process, the method comprising: providing a cathodic tool and an anodic workpiece defining a working gap therebetween, the cathodic tool and the workpiece being at least partially immersed in a conductive electrolyte solution; providing a negative electrical potential to the cathodic tool; monitoring one or more of the electrical potential, current, current density and charge between the cathodic tool and the anode to determine the working gap between the cathodic tool and the anode; and, controlling one or more process parameters to maintain one or more of the working gap and electrochemical working conditions between the cathodic tool and anodic workpiece at a targeted value.

First claim

1 . A method of controlling a working gap between one or more cathodic tools and an anodic workpiece in an electrochemical material dissolution process, the method comprising:
providing a cathodic tool and an anodic workpiece defining a working gap therebetween, the cathodic tool and the anodic workpiece being at least partially immersed in a conductive electrolyte solution; providing a negative electrical potential to the cathodic tool; monitoring one or more of the electrical potential, current, current density and charge between the cathodic tool and the anodic workpiece to determine the working gap between the cathodic tool and the anodic workpiece; and, controlling one or more process parameters to maintain one or more of the working gap and electrochemical working conditions between the cathodic tool and the anodic workpiece at a targeted value.

2 . A method as claimed in claim 1 , wherein the anodic workpiece is at least partially comprised of a metallic material.

3 . A method as claimed in claim 1 , wherein the anodic workpiece comprises a metallic aerospace article such as, for example, a casing, pipe, disc, bladed disk, drum, bladed drum, ring, bladed ring or aerofoil.

4 . A method as claimed in claim 1 , the process parameters comprising, for example, one or more of working gap, electrical potential, current, current density, charge, resistance, cathodic tool feed rate, processing time, cathodic tool depth, electrolyte flow rate and/or pressure, temperature and electrolyte chemistry.

5 . A method as claimed in any claim 1 , wherein the controlling step comprises comparing or correlating one or more of the electrical potential, current, current density and charge between the cathodic tool and the anodic workpiece with sample or real-time data to convert the monitored electrical output into an estimation of the working gap.

6 . A method as claimed in claim 1 , wherein the monitoring system comprises one or more of a drive, actuation, spring, resilient member or reciprocating mechanism to increase or decrease the working gap according to the monitored electrical output.

7 . A method as claimed in any claim 1 , wherein one or more of the cathodic tools comprises a plurality of cathodic heads.

8 . A method as claimed in claim 7 , wherein the working gap of the cathodic heads is independently varied according to pre-set points, electrochemical working conditions or offset values.

9 . A method as claimed in any of claim 7 , wherein the or each cathodic head comprises an insulating tip, guide portion or member to provide the working gap between each of the one or more cathodic heads and the anodic workpiece.

10 . A method as claimed in claim 1 wherein the electrolyte has a pH of 7 or less.

11 . A method as claimed in claim 1 wherein the electrolyte has a pH of 7 or more.

12 . A method as claimed in claim 1 wherein the electrolyte comprises a molten salt solution.

13 . A method as claimed in claim 1 wherein a facing surface of the or each cathodic tool or head is at least partially contoured, the facing contour of the or each cathodic tool or head at least partially replicating the desired shape of at least a portion of the anodic workpiece.

14 . An electrochemical material dissolution apparatus configured to remove material from a surface of an anodic workpiece, the apparatus comprising:
at least one cathodic tool; an electrical source configured to provide one or more of a controllable voltage and a controllable current to the cathodic tool; an electrical detection device configured to monitor one or more of electrical potential, current density, charge and current applied to the cathodic tool so as to determine a working gap between the cathodic tool and the anodic workpiece; the electrical detection device further comprising a feedback and actuation system configured to control process parameters to maintain one or more of the working gap and electrochemical working conditions between the cathodic tool and the anodic workpiece at a targeted value.

Assignees

• Rolls Royce Plc

Inventors

• Clark Daniel
• Walpole Andrew R

Classifications

• B23H9/10

  Working turbine blades or nozzles · CPC title

• C25F3/16

  Polishing · CPC title

• C25F7/00 Primary

  Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects (for both electrolytic coating and removal C25D); Servicing or operating · CPC title

• B23H7/18 Primary

  for maintaining or controlling the desired spacing between electrode and workpiece · CPC title

• B23H3/04

  Electrodes specially adapted therefor or their manufacture (B23H9/00 takes precedence) · CPC title