| 摘要 |
PURPOSE:To easily and certainly mold a perforated plate with projections for separating minute water droplets from the driving steam of a steam turbine, by forming a stepped hole having a small pierced opening, which is provided to the center of the bottom part thereof, to the single surface of a base plate and applying pipe expanding treatment to said bottom part. CONSTITUTION:A stepped hole 10 having an inner diameter D1 and the bottom part 12 of the stepped hole 10 provided with an opening having an inner diameter (d) are molded to one surface of a base plate 1a (a first process). On the other hand, a ring shaped notch groove 13, which is concentric to the stepped hole 10 and has a diameter larger than the inner diameter D1 of the stepped hole 10 and a proper oblique notch angle theta, is molded to the other surface of the base plate 1a (a second process). A pipe expanding tool such as a pipe expander is used from the side of the large diameter D1 of the stepped hole 10 to protrude and mold a cylindrical part 14 through the central small pierced opening 11 of the bottom part 12 (a third process). A diameter expanding tool such as a conical rotary tool is pressed to the interior of the cylindrical part 14 from the other surface side of the base plate 1a and rotated to mold the cylindrical part 14 into a trumpet shaped projection 7' and a desired perforated plate with trumpet shaped projections is obtained (a fourth process).
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