A process for cold working of the inner surface of a bore in a centrifugal compressor wheel along only a fractional portion of the bore length (i.e., along less than a full axial length of the bore), thereby creating a zone of compressive residual hoop stress in the metal surrounding the bore where the wheel needs the beneficial residual stress. The process purposefully avoids cold working of the bore at locations adjacent to high-stress areas and features of the wheel, where cold working in such locations could negatively impact the wheel's overall life.

A process for treating a centrifugal compressor wheel includes a combination of cold expansion of at least part of the bore of the wheel to induce residual compressive stresses in a region around the bore, and surface peening at least parts of the compressor wheel such as the back disk and portions of the blades.

A motor rotor and a method for manufacturing a motor rotor, enabling crimping of the resolver rotor at low cost with less influence on the detection accuracy. A motor rotor includes a resolver rotor and a rotor shaft to which the resolver rotor is affixed by crimping. The rotor shaft includes a first stepped section with which a crimping punch makes contact to deform the first stepped section, a second stepped section with which an end surface of the resolver rotor makes contact, and a cutout groove formed in a surface which is located near the first stepped section and with which an inner peripheral hole section of the resolver rotor makes contact. In the crimping operation, the first stepped section of the rotor shaft is bent within the cutout groove to form a crimping protrusion which presses the end surface of the resolver rotor.

A motor rotor and a method for manufacturing a motor rotor, enabling crimping of the resolver rotor at low cost with less influence on the detection accuracy. A motor rotor includes a resolver rotor and a rotor shaft to which the resolver rotor is affixed by crimping. The rotor shaft includes a first stepped section with which a crimping punch makes contact to deform the first stepped section, a second stepped section with which an end surface of the resolver rotor makes contact, and a cutout groove formed in a surface which is located near the first stepped section and with which an inner peripheral hole section of the resolver rotor makes contact. In the crimping operation, the first stepped section of the rotor shaft is bent within the cutout groove to form a crimping protrusion which presses the end surface of the resolver rotor.

A forging apparatus and method is disclosed in which an extrusion punch is held between an upper press and a lower press and propelled towards a billet by a ram to form an extruded shaped component. The extrusion punch has a striking face in which a recess is formed. During the extrusion process, material from the billet enters the recess so as to lock the extrusion punch and the shaped component together. Accordingly the shaped component is not lifted up with the upper press when it is separated from the lower press and so the position of the shaped component after the forging extrusion operation is known accurately and reliably.

A forging apparatus and method is disclosed in which an extrusion punch is held between an upper press and a lower press and propelled towards a billet by a ram to form an extruded shaped component. The extrusion punch has a striking face in which a recess is formed. During the extrusion process, material from the billet enters the recess so as to lock the extrusion punch and the shaped component together. Accordingly the shaped component is not lifted up with the upper press when it is separated from the lower press and so the position of the shaped component after the forging extrusion operation is known accurately and reliably.

The invention discloses a process of manufacturing heavy and critical components such as a blowout preventer (BOP) with a combination of open die forging, piercing and machining process which results in to better material utilization and saving in the machining time. The forging process of the invention involves a step of notching, wherein a transverse notch is made near each end of the ingot before cogging said ingot. The invention allows development of safety and critical components with effective material utilisation.

A process for treating a centrifugal compressor wheel includes a combination of cold expansion of at least part of the bore of the wheel to induce residual compressive stresses in a region around the bore, and surface peening at least parts of the compressor wheel such as the back disk and portions of the blades.

A silencing device includes: a flow path forming plate having a flow path forming surface for forming a wall surface of a flow path through which fluid flows; and a cavity defining portion for defining a cavity on the reverse surface side of the flow path forming plate, the reverse surface being located on the reverse side of the flow path forming surface. The flow path forming plate has formed therein a plurality of fine through-holes which are configured to provide communication between the flow path forming surface and the reverse surface and which has a diameter from 0.01 mm to 0.5 mm.

A silencing device includes: a flow path forming plate having a flow path forming surface for forming a wall surface of a flow path through which fluid flows; and a cavity defining portion for defining a cavity on the reverse surface side of the flow path forming plate, the reverse surface being located on the reverse side of the flow path forming surface. The flow path forming plate has formed therein a plurality of fine through-holes which are configured to provide communication between the flow path forming surface and the reverse surface and which has a diameter from 0.01 mm to 0.5 mm.