Electrolytic etching apparatus and method for marking metal tubes with

Abstract

An electrolytic etching apparatus employs a continuous stencil imprinted with a sequence of identification numbers and includes spaced spools and upper and lower electrodes defining an etching station located between the spools. The stencil extends between the spools and is moved by rotatably indexing the spools to position successive ones of the identification numbers over the lower electrode for etching on a successive one of the metal tubes. A wicking pad is draped over the lower electrode below the stencil and has one end extending into a reservoir of electrolyte also located below the stencil. The wicking pad draws up electrolyte by capillary action to provide a steady flow of the electrolyte to the portion of the wicking pad located directly below a portion of the stencil located at the etching station. The upper electrode is mounted for movement toward and away from the lower electrode and the wicking pad and stencil portions. One tube to be marked is placed between the upper electrode and the stencil portion. The upper electrode is moved downwardly to press the tube against the stencil portion and thereby against the wicking pad portion and lower electrode. A voltage is then applied to the upper and lower electrodes for causing the electrolytic etching action to occur and mark one identification number on the surface of the tube.