ETCHING EQUIPMENT

PURPOSE:To speed up the piercing, by etching, of a sheet metal as a material by forming a pushing-down roller for a strip-like material into a specific structure at the time of forming a resist film on a sheet metal as a shadow mask material for a color cathode-ray tube and carrying out piercing by etching while undulatingly moving the above sheet metal in a longitudinal direction. CONSTITUTION:Resist films having open patterns 20 corresponding to electron beam passing holes are formed on the upper and lower surfaces of a low-carbon steel strip as a shadow mask material for a color cathode-ray tube. This steel strip 1 is moved in a longitudinal direction wile forming this steel strip 1 into a wavy state by means of pushing-down rollers 21a and pushing-up rollers 21b and subjected to piercing treatment corresponding to the open patterns 20 by using an etchant consisting of an FeCl3 solution. At this time, the amount of FeCl2 formed by the deterioration of the etchant FeCl3 due to use is increased in the pushing-down roller 21a part and a liquid puddle 10 is formed in the pushing-down roller 21a part, by which etching reaction is retarded. By providing the pushing-down roller with annular grooves 23a, 23b in a peripheral direction and also plural straight-line grooves 24 in a roller-shaft direction, the deteriorated etchant in the liquid puddle 10 is rapidly removed and piercing treatment can be rapidly carried out always with fresh etchant.