A novel manufacturing method for functionally graded component includes a cold sprayed additive manufactured core material and a cold sprayed additive manufactured set of teeth around said core made from another material.

The invention relates to a method for machining a rack and to a rack (1) machined according to said method, for example a steering rack. In said method, the stress pattern that is present after hardening and/or straightening the rack and that has a chaotic internal stress distribution of tensile and compressive stresses is converted into a stress pattern that optimizes the strength and the use of the material and also the diameter of the rack, such that, without altering the structure, at least the region of the gear teeth (2) is pre-stressed, in a functionally combined series of steps of a machining pass, with a deliberately introduced internal compressive stress without tensile stress and with a predominantly uniform stress distribution or stress plane.

The present disclosure provides a method for manufacturing a gear capable of processing a projection formed on a tooth tip by shot peening while reducing time for manufacturing the gear. A method for manufacturing a gear includes: a process of hardening, by performing shot peening in which shot particles are jetted onto a tooth surface 1a of a gear base material, the tooth surface while applying residual stress to the tooth surface; a process of softening, by at least heating a tooth tip of the gear base material having the hardened tooth surface, the tooth tip; and a process of rotationally driving the gear base material having the softened tooth tip by engaging it with another gear.

Metal components subject to wear or contact fatigue in a first area, and subject to bending, axial and/or torsional stress loading in a second area comprise a surface hardened, first surface layer in the first area; and a surface compressive-stress treated, second surface layer in the second area. The second surface layer has a material hardness different from, and typically lower than the first surface layer, and induced residual compressive stress to improve fatigue strength. Example components described include a gear, a cog, a pinion, a rack, a splined shaft, a splined coupling, a torquing tool and a nut driving tool. A hybrid manufacturing process is described, including area-selective surface hardening combined with a process to add compressive stress to fatigue failure prone areas.

Metal components subject to wear or contact fatigue in a first area, and subject to bending, axial and/or torsional stress loading in a second area comprise a surface hardened, first surface layer in the first area; and a surface compressive-stress treated, second surface layer in the second area. The second surface layer has a material hardness different from, and typically lower than the first surface layer, and induced residual compressive stress to improve fatigue strength. Example components described include a gear, a cog, a pinion, a rack, a splined shaft, a splined coupling, a torquing tool and a nut driving tool. A hybrid manufacturing process is described, including area-selective surface hardening combined with a process to add compressive stress to fatigue failure prone areas.

A mechanical structural component is a toothed component obtained by performing cold forging and carburizing treatment on a steel having a predetermined chemical composition, in prior austenite grains after the carburizing treatment, an area ratio of crystal grains of 50 m or less is 80% or more, and an area ratio of crystal grains exceeding 300 m is 10% or less, and a total helix deviation of teeth after the carburizing treatment satisfies Formula (1)
(B.sub.max/L)10.sup.35(1)
where B.sub.max is a maximum total helix deviation in all teeth in mm, and L is a face width in mm.

A mechanical structural component is a toothed component obtained by performing cold forging and carburizing treatment on a steel having a predetermined chemical composition, in prior austenite grains after the carburizing treatment, an area ratio of crystal grains of 50 m or less is 80% or more, and an area ratio of crystal grains exceeding 300 m is 10% or less, and a total helix deviation of teeth after the carburizing treatment satisfies Formula (1)
(B.sub.max/L)10.sup.35(1)
where B.sub.max is a maximum total helix deviation in all teeth in mm, and L is a face width in mm.

A modular pinion shaft that includes a tubular member having a first end and a second end, a first pinion gear member secured to the first end by a plurality of fasteners, and a second pinion gear member secured to the first end by a plurality of fasteners. Gear teeth of each of the pinion gear members are aligned by one or more indexing members disposed between the tubular member and each pinion gear member.

A modular pinion shaft that includes a tubular member having a first end and a second end, a first pinion gear member secured to the first end by a plurality of fasteners, and a second pinion gear member secured to the first end by a plurality of fasteners. Gear teeth of each of the pinion gear members are aligned by one or more indexing members disposed between the tubular member and each pinion gear member.

In a steered shaft in a steering system, when a section of a first end portion having a prescribed length shorter than a length from an end face to an outer peripheral rolling groove is defined as a first section, a section of the first end portion other than the first section and adjacent to the outer peripheral rolling groove is defined as a second section, a section, in the outer peripheral rolling groove, starting from a boundary between the second section and the outer peripheral rolling groove and having a prescribed length shorter than an axial length of a section along which the outer peripheral rolling groove extends is defined as a third section, a maximum value of a hardening depth in the second section is larger than a hardening depth in the first section.