According to an embodiment, a method of correcting a bend of a joint type-turbine rotor comprises: measuring displacement of a convex portion of the bend at a joined portion of the joint type-turbine rotor or displacement of a surface opposite to the convex portion in a circumferential direction of the joint type-turbine rotor; heating the convex portion; and cooling the joined portion after the step of heating. The steps of heating and cooling are performed during the step of measuring.

According to an embodiment, a method of correcting a bend of a joint type-turbine rotor comprises: measuring displacement of a convex portion of the bend at a joined portion of the joint type-turbine rotor or displacement of a surface opposite to the convex portion in a circumferential direction of the joint type-turbine rotor; heating the convex portion; and cooling the joined portion after the step of heating. The steps of heating and cooling are performed during the step of measuring.

A fan structure includes a first fixing ring and a plurality of fan blades. The first fixing ring includes a plurality of first recesses radially arranged on the first fixing ring. One side of the fan blades is coupled to the first recesses of the first fixing ring. The first fixing ring includes a stamped part and a non-stamped part, in which the stamped part is in contact with the fan blades, and the thickness of the stamped part is smaller to the thickness of the non-stamped part.

A device for circulating wastewater is received in a tank, in which a conical or hyperboloid-like stirring body is mounted on a vertical stirring shaft, wherein the stirring body is composed from a plurality of segments produced from metal along radially extending joining zones.

An impeller, particularly for centrifugal pumps, including a front plate and a back plate arranged coaxially to a central axis of the impeller and rigidly connected to each other by a plurality of radial blades which are angularly distributed about the central axis; the front plate has a central through opening adapted to connect the impeller to a driving shaft; the impeller includes a reinforcement portion that extends perimetrically to the through opening, at least partially surmounting the front plate; the front plate and the reinforcement portion are constituted by a single part formed by stamping, bending and flattening a metal sheet.

A stirring body has a hyperboloid-like or truncated cone-like form and a central connector piece for connection to a stirring shaft. To simplify the production of the stirring body and to reduce the transport outlay, it is proposed for the stirring body to be formed from a plurality of segments which are interconnected along joining zones extending from a peripheral edge in the direction of the connector piece.

A fan structure includes a first fixing ring and a plurality of fan blades. The first fixing ring includes a plurality of first recesses radially arranged on the first fixing ring. One side of the fan blades is coupled to the first recesses of the first fixing ring. The first fixing ring includes a stamped part and a non-stamped part, in which the stamped part is in contact with the fan blades, and the thickness of the stamped part is smaller to the thickness of the non-stamped part.

Disclosed are an integrally formed fan guard and its manufacturing method. The fan guard includes a top side and a circumferential side around the outer periphery of the top side, and the top and circumferential sides are formed by a metal plate by a single or multiple stamping and extrusion method. An air hole is formed by stamping at the top side or both of the top and circumferential sides for flowing air, and a central through hole is formed at the center position of the top side. In the manufacturing method, the fan guard is formed by stamping or extruding a steel plate directly by stamping and extrusion equipments. The invention does not require a high welding skill, and the fan guard so manufactured has the advantages of high efficiency, consistency, and pass rate, and thus reducing the production cost significantly.

The invention relates to a stirring body, in particular for generating a current in a wastewater treatment tank, stirring body having a hyperboloid-like or truncated cone-like form and a central connector piece for connection to a stirring shaft. To simplify the production of the stirring body and to reduce the transport outlay, it is proposed in accordance with the invention for the stirring body to be formed from a plurality of segments which are interconnected along joining zones extending from a peripheral edge in the direction of the connector piece.

Embodiments of an apparatus, system, method and techniques are described for an improved volumetric resistance blower and rotor. An apparatus may comprise, for example a motor, a casing having one or more inlets and one or more outlets, and a cylindrical rotor to create a volumetric resistance inside the casing, at least a portion of the rotor comprising a porous material. Other embodiments are described.