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.

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 torsion bar includes a central portion extending in an axial direction about a longitudinal axis. The torsion bar also includes a first end portion having a splined outer surface, the first end portion disposed proximate a first end of the torsion bar, the first end portion spaced from the central portion with a first annular groove extending circumferentially about the torsion bar.

A method of manufacturing a torsion bar is provided. The method includes cutting a stock torsion bar material to a desired torsion bar length to form the torsion bar. The method also includes forming a first end portion by removing material from the torsion bar to form a first annular groove extending circumferentially about the torsion bar. The method further includes forming a second end portion by removing material from the torsion bar to form a second annular groove extending circumferentially about the torsion bar.

To provide a method of manufacturing a shaft for a steering device, the shaft including a spline shaft part to be coupled with an input shaft, a stopper part to be coupled with an output shaft, and an intermediate shaft part that couples the spline shaft part with the stopper part. The method includes: a step of forming a hole part recessed in an axial direction from one end of a pillar-shaped material by forging; and a step of pressing the material in which the hole part has been formed into a die to perform drawing in a radial direction on a portion of the material at which the stopper part is formed and prolonging a length along the axial direction of the hole part at the same time by forging.

In a method for monitoring a functional state of a shaping tooth arrangement on a forming tool, at measurement times which are temporally staggered with respect to each other at a plurality of measurement locations on the shaping tooth arrangement, a tooth arrangement force is measured which acts on the shaping tooth arrangement. At each of the measurement times for each of the measurement locations an instantaneous local tooth arrangement force is thereby determined. A previous instantaneous local tooth arrangement force and a subsequent instantaneous local tooth arrangement force are correlated with each other to determine a local state identification value. On the basis of the local state identification values associated with the measurement locations, information is obtained relating to the functional state of the shaping tooth arrangement.

To provide a method of manufacturing a shaft for a steering device, the shaft including a spline shaft part to be coupled with an input shaft, a stopper part to be coupled with an output shaft, and an intermediate shaft part that couples the spline shaft part with the stopper part. The method includes: a step of forming a hole part recessed in an axial direction from one end of a pillar-shaped material by forging; and a step of pressing the material in which the hole part has been formed into a die to perform drawing in a radial direction on a portion of the material at which the spline shaft part and the intermediate shaft part are formed, and prolonging a length along the axial direction of the hole part at the same time by forging.

A method for manufacturing a gear toothing on a metallic workpiece and a tool device for calibration of a gear toothing inlet and/or a gear toothing outlet of a gear of the metallic workpiece. The method includes producing the gear toothing by forming manufacturing and performing a compression process to calibrate a gear toothing inlet and/or a gear toothing outlet of the gear toothing, wherein a gear tooth shape and a gear tooth length are adjusted during the compression process. The tool device includes a workpiece location for accommodating the workpiece, an axially movable die selectively engageable with the gear toothing, the die supporting the gear toothing and predefining the gear tooth shape to be adjusted on the gear toothing inlet and/or on the gear toothing outlet, and at least one axially movable compression ring which calibrates the gear toothing inlet and/or gear toothing outlet by a compression process.

A one-piece axle and a method of manufacture. The method may include providing a one-piece axle blank that has a shaft and a flange. The shaft may have a hole that may extend along an axis. The flange may extend radially outward from an end of the shaft. The shaft may be radially forged against a first mandrel to axially elongate the shaft.

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.