| 摘要 |
PURPOSE:To permit production of a knife mold for forming slits of a seal which is seamless and can be mounted to a cylindrical barrel by supplying an etching soln. with a supply device provided with a pressure regulating means for setting a liquid pressure in two stages to a means for injecting the etching soln. toward the steel sheet on a mounting plate in a housing provided internally with an etching chamber. CONSTITUTION:The steel sheet 20 which is the material to be treated drawn with a construction line with the photoresist agent corresponding to a knife-edge shape on the surface is mounted to the mounting plate 22 exposed by opening a cap body 14 of an apparatus 10 for production. The cap body 14 is then closed and the operation of the 1st etching is started by directing the surface to be treated of the steel sheet 20 downward in the etching chamber 18 in the housing 12. The etching soln. regulated to a prescribed high pressure by pressure regulating valves is injected from respective injection nozzles 34 through supply pipes 36 toward the steel sheet 20 upon starting of said operation. As a result, the knife edge part of the shape which is of a peak shape in section and is constricted near the peak is formed. After the photoresist agent is removed by opening the cap body 14, the 2nd etching is executed in the same manner as mentioned above by the etching soln. regulated to the high pressure higher than the prescribed high pressure mentioned above, by which the sharp knife edge part is formed.
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