Ebara Corporation

Isamu Ichiki

Shinichiro Arakawa

A centrifugal pump casing of a centrifugal pump, includes a casing shell accommodating a rotary impeller therein and having as a basic circle an inner peripheral circle having a diameter greater than the diameter of the outer peripheral circle of the impeller. A bulged portion bulged radially outwardly is integrally formed on the outer peripheral wall of the casing shell, the bulged portion extends from a starting point remote from the winding starting point of the casing shell in a circumferential direction to an end point while gradually increasing in height in the direction from the starting point to the end point. A pipe-like discharge nozzle is connected with the casing shell so that it extends between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed. In this arrangement, since the bulge height above the basic circle is not so great even at the end point where a maximum height is reached, the bulged portion can be formed through only one pressing process without the need for an annealing process. Further, since the difference in height between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed is not so great, the wall portion of the casing shell at the winding starting point can serve as a guide; and accordingly, a guide for discharge water which is required in the prior art may be eliminated.

Method of manufacturing a centrifugal pump casing

A centrifugal pump casing of a centrifugal pump, comprising a casing shell accommodating a rotary impeller therein and having as a basic circle an inner peripheral circle having a diameter greater than the diameter of the outer peripheral circle of the impeller is disclosed. A bulged portion bulged radially outwardly is integrally formed on the outer peripheral wall of the casing shell, the bulged portion extends from a starting point remote from the winding starting point of the casing shell in a circumferential direction to an end point while gradually increasing in height in the direction from the starting point to the end point. A pipe-like discharge nozzle is connected with the casing shell so that it extends between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed. In this arrangement, since the bulge height above the basic circle is not so great even at the end point where a maximum height is reached, the bulged portion can be formed through only one pressing process without the need for an annealing process. Further, the wall portion of the casing shell at the winding starting point can serve as a guide, and accordingly, a guide for discharge water which is required in the prior art may be eliminated.

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Yokohama, Japan

Isamu Ichiki