| 摘要 |
<p>A pump casing manufactured by press forming of steel plate and including a volute casing encircling a pump impeller so as to form a fluid path around the pump impeller is disclosed. The cross-sectional area of the fluid path is gradually increased towards an discharge port of the pump casing. The pump casing includes a casing body (21) which is formed at first by press forming a metal plate into a cylindrical cup shape having an opening portion at one side thereof and a closed bottom portion at the other side of the same, and then by press forming the cylindrical cup shaped casing body so as to have a volute portion (21a) radially outwardly expanded from a cylindrical surface of the casing body (21) at an axially intermediate portion thereof radially opposite to the pump impeller, a casing flange (21b) outwardly extending from the opening portion and an aperture serving as a suction port (21d) at the bottom portion.</p> |
