Provided is a hollow rack bar including a rack portion that is engaged with a pinion gear and faces supported by a yoke. The hollow rack bar includes: the rack portion engaged with the pinion gear; and the supported faces provided on a back side of teeth of the rack portion and supported by the yoke. The rack portion is formed by locating a toothed mold on an outer face of a circular tube material, and inserting a cored bar into the circular tube material to pressurize an inner face, thereby transferring a shape of the toothed mold. The supported faces are formed by removal processing or deformation processing of a back side of the teeth rack portion of the circular tube material.

A method for manufacturing a rack bar having a first rack and a second rack is provided. The first and second racks have an angular positional difference around an axis of the rack bar. The method includes forming a first flat surface and a second flat surface on an outer circumference of a single hollow shaft member, with the angular positional difference being provided between the first and second flat surfaces, and forming the first rack on the first flat surface and the second rack on the second rack surface by press-fitting one or more mandrels into the hollow shaft member in a state in which one or more teeth dies corresponding to the first rack and the second rack is pressed against the first flat surface and the second flat surface.

Various implementations include a method of manufacturing a ring molded article. The ring molded article has two convex portions which respectively protrude on both sides of the ring molded article in a direction of a center axis thereof and extend in a direction of a circumference of the ring molded article. The ring material is placed inside two molds on which concave portions respectively corresponding to the convex portions are formed. The ring material is supported by a region on an outer peripheral side from an outer peripheral side corner in the concave portion of one of the two molds and a region on an inner peripheral side from an inner peripheral side corner in the concave portion of another of the two molds. The ring material is then forged so as to be pressed by the two molds in a direction of a center axis of the ring material.

A method of manufacturing an outer joint member of a constant velocity universal includes forming cup and shaft members of medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed by forging, and a joining end surface formed on an outer surface of the bottom portion after the forging, preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member, and bringing the joining end surfaces of the cup and shaft members into abutment against each other. The method also includes welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member.

Solid metal protrusions are formed by the method including: clamping and fixing the metal workpiece between a support die and a pressure die; pressing end cross sections of two or more outer peripheral end parts of the metal workpiece fixed between the support die and the pressure die at a temperature lower than a softening point of a metal used as the metal workpiece from a direction perpendicular or oblique to an upright direction of the protrusions to be formed on one surface of the metal workpiece by press molding using a pressing die or a pressing jig; undergoing plastic flows of metal into through-holes formed as recessed parts that serve as female molds for forming the protrusions in at least one of the support die and the pressure die; and forming solid protrusions on the surface of the metal workpiece.

A forging apparatus includes an ironing mechanism and a phase alignment mechanism. The ironing mechanism includes: a punch set, which is fitted into a cylindrical portion of a pre-processing material to be formed into the outer joint member, and is radially expandable and contractible, the cylindrical portion having grooves formed in an inner peripheral surface thereof; and a die having a hole into which the cylindrical portion is press-fitted. The phase alignment mechanism is configured to align phases of the grooves in the inner peripheral surface of the pre-processing material and phases of track groove portion forming surfaces of the punch set with each other before the pre-processing material is fitted to the punch set.

To provide a method for manufacturing a rack that can reduce the manufacturing cost, the method comprises the following processes. An intermediate material 18a having a concave groove 42y in part in the radial direction of the outer circumferential surface that extends in the axial direction and is recessed inward in the radial direction is obtained. A plurality of rack teeth 10z are formed on an opposite surface to the concave groove 42y with respect to the radial direction of the outer circumferential surface of the intermediate material 18a by pressing the teeth-forming concave and convex section 28 that have a concave and convex configuration with respect to the axial direction in a state where the portions on both sides of the concave groove 42y of the outer circumferential surface of the intermediate material with respect to the circumferential direction are constrained and the inner surface of the concave groove 42y is not constrained.

Outer ball grooves of an outer joint member of a constant velocity joint each have a first ball groove for allowing a ball to roll therein when the constant velocity joint operates, and a second ball groove having a ball groove radius larger than a ball groove radius of the first ball groove. The second ball groove has a curved line and a connecting line. The curved line is connected to a groove bottom end of the first ball groove located closer to an opening of the outer joint member and is curved radially outward in a concave manner. The connecting line connects the curved line and the opening. The curved line is curved with a curvature center that is located closer to the opening than the groove bottom end of the first ball groove and that is located radially inside the outer joint member.

Provided are a method of manufacturing a hollow rack bar including a rack portion that is engaged with a pinion gear and faces supported by a yoke easily and accurately, and the hollow rack bar. The hollow rack bar (10) includes: the rack portion (21) engaged with the pinion gear (29); and the supported faces (23) provided on a back side of teeth of the rack portion (21) and supported by the yoke (31). The rack portion (21) is formed by locating a toothed mold (39) on an outer face of a circular tube material, and inserting a cored bar (41) into the circular tube material to pressurize an inner face, thereby transferring a shape of the toothed mold (39). The supported faces (23) are formed by removal processing or deformation processing of a back side of the teeth rack portion (21) of the circular tube material.

A method can be employed to produce a rack for a steering gear. The rack may include a toothed portion with a toothing, and a shaft portion with a functional portion. Separate segments comprising at least one in each case bar-shaped toothed segment and one shaft segment may be provided, which are aligned on a common longitudinal axis and are connected to one another at a joint. The method may involve providing a shaft raw material piece having a length that is a multiple of a shaft segment length, continuously grinding a part of a circumferential face of the shaft raw material piece across a multiple of the shaft segment length to produce a semi-finished shaft segment product, cutting to length a shaft segment from the semi-finished shaft segment product, providing a toothed segment, and joining the shaft segment to the toothed segment.