A shaft for a steering device has a first portion, a second portion, and a third portion that is a shaft integrated with the first portion and the second portion and couples the first portion and the second portion in a first direction. The outer diameter of the third portion is smaller than the length of the second portion in a second direction intersecting with the first direction, and is constant across a direction extending along the first direction. The hardness of the third portion is greater than the hardness of the second portion, and is constant across the direction extending along the first direction.

A shaft member includes: an outer peripheral surface; at least one axial side surface facing an axial direction; a chamfered portion formed at a connection portion between an axial end edge of the outer peripheral surface and an outer peripheral edge of the axial side surface; and a processing target portion formed on at least a part of the outer peripheral surface. The chamfered portion includes at least one supported surface portion disposed at an axially intermediate portion of the chamfered portion and inclined radially outward as approaching the processing target portion in the axial direction. The axial end edge of the outer peripheral surface and the outer peripheral edge of the axial side surface are located radially inward than a tangent line at an axially intermediate portion of the supported surface portion, in a cross section in the axial direction.

Provided are a hollow drive shaft using an upsetting method and a method of manufacturing the same, in which hot forging and upsetting processes are applied to both ends of a workpiece so that an outer diameter at both ends of the workpiece is greater than an outer diameter of a middle part of the workpiece, thereby reducing a weight of the drive shaft and enabling the drive shaft to transmit higher driving power. According to the present invention, the upsetting process is applied during the hot forging process to manufacture the hollow drive shaft, portions to be substantially processed are limited to portions at both ends of the workpiece, and the number of upsetting processes is limited to a minimum number (2 or the like), such that initial investment costs and manufacturing costs are low because the number of processes is small.

A method for manufacturing a rotor shaft for an electrical aggregate, including providing a pin having a shaft plug-in, in particular a cylindrical shaft plug-in; producing a hollow rotor shaft body being open at least at a first end for receiving the pin and in form of a rotary body, where an oversize exists between at least one outer surface of the shaft plug-in and at least one inner surface of the rotor shaft body; and inserting the shaft plug-in into the rotor shaft body for fastening the pin to the rotor shaft body for finishing the rotor shaft, such that the process and operation of manufacturing a rotor shaft is simplified while at the same time reducing costs and material waste, and to produce a rotor shaft that can withstand high loads and transmit high torques.

In a method for thickening a plastically deformable hollow body wall of a hollow body, with effective radial support of the unthickened hollow body wall on an outer supporting face of an outer mold and with effective radial support of the hollow body wall on an inner supporting face of an inner supporting body, the hollow body is acted on by a compressive force by two application members at application points by moving the application members towards one another in the axial direction with a compressing movement. The application points on the hollow body are distanced from one another in the axial direction. An expansion space of the outer mold is arranged between the application points. Due to the compressing movement of the application members, material of the hollow body wall between the application points is plasticised in the region of the expansion space of the outer mold, and plasticised material of the hollow body wall flows into the expansion space of the outer mold, thus thickening the hollow body wall.

The present disclosure relates to a steel forging process, in particular a hot steel forging process in horizontal press of a metal tube, preferably a cylindrical steel tube.

A heating/heat-retaining device, particularly to a heating/heat-retaining device used in the forging process, and more particularly to an opening-and-closing type heater and a wind generator shaft forging process using the same. The opening-and-closing type heater comprises a base, a tube body mounted on the base and a tube body opening-and-closing mechanism; the tube body comprises a fixed tube body and a movable tube body, the fixed tube body and the movable tube body are arc-shaped shells, and form a hollow shape when the openings thereof match with each other; the tube body opening-and-closing mechanism is connected to the movable tube body for realizing the opening-and-closing of the movable tube body and the fixed tube body. The invention solves heat retaining and heating problems during the forging process of the main shaft forgings and avoids internal defects due to rapid temperature drop of the main shaft forgings.

A heating/heat-retaining device, particularly to a heating/heat-retaining device used in the forging process, and more particularly to an opening-and-closing type heater and a wind generator shaft forging process using the same. The opening-and-closing type heater comprises a base, a tube body mounted on the base and a tube body opening-and-closing mechanism; the tube body comprises a fixed tube body and a movable tube body, the fixed tube body and the movable tube body are arc-shaped shells, and form a hollow shape when the openings thereof match with each other; the tube body opening-and-closing mechanism is connected to the movable tube body for realizing the opening-and-closing of the movable tube body and the fixed tube body. The invention solves heat retaining and heating problems during the forging process of the main shaft forgings and avoids internal defects due to rapid temperature drop of the main shaft forgings.

Provided are a hollow drive shaft using an upsetting method and a method of manufacturing the same, in which hot forging and upsetting processes are applied to both ends of a workpiece so that an outer diameter at both ends of the workpiece is greater than an outer diameter of a middle part of the workpiece, thereby reducing a weight of the drive shaft and enabling the drive shaft to transmit higher driving power. According to the present invention, the upsetting process is applied during the hot forging process to manufacture the hollow drive shaft, portions to be substantially processed are limited to portions at both ends of the workpiece, and the number of upsetting processes is limited to a minimum number (2 or the like), such that initial investment costs and manufacturing costs are low because the number of processes is small.

A drive shaft includes a first annular wall and a second annular wall joined together via a friction-welded portion. The first annular wall and the second annular wall have outer diameters of 30 to 50 mm and wall thicknesses of 3 to 5 mm. A burr created at the friction-welded portion has a connection radius of greater than or equal to 0.5 mm, a base radius of greater than or equal to 0.5 mm, a burr base angle of less than or equal to 40°, and a burr slope length of 0.2 to 5 mm.