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.

The objective of the present invention is to improve the rigidity of a vehicle knuckle made from an aluminum alloy with respect to a force directed from the outside to the inside in the width direction of a vehicle. A vehicle knuckle (11) is provided with a bearing support portion (111), a knuckle upper portion (113) and a knuckle lower portion (112). With the vehicle knuckle (11) in a position fitted to a vehicle main body, the knuckle upper portion (113) has a shape in which, if the knuckle upper portion (113) is divided equally into five or more regions in a vertical direction, and the center of the bearing support portion (111) is fixed and a horizontal load F is applied to a knuckle upper end portion (115) from the outside toward the inside in the width direction of the vehicle, the minimum value of a value obtained by dividing the strain energy in each of the five or more regions other than a first region (11A) by the mass of the corresponding region is at least equal to 0.70 times the maximum value thereof.

A method of manufacturing an elevator safety spring is provided. The method includes determining a plurality of dimensional parameters of the elevator safety spring. The method also includes selecting a plurality of dimensions within the dimensional parameters. The method further includes manufacturing the elevator safety spring based on the selected parameters, the elevator safety spring having an I-beam cross-section.

A method of manufacturing an elevator safety spring is provided. The method includes determining a plurality of dimensional parameters of the elevator safety spring. The method also includes selecting a plurality of dimensions within the dimensional parameters. The method further includes manufacturing the elevator safety spring based on the selected parameters, the elevator safety spring having an I-beam cross-section.

Various implementations include a ring material used for producing a ring molded article. The ring molded article has two convex portions which respectively protrude on opposite 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. A straight line passing through centers of gravity of first and second side regions is inclined by an angle relative to the center axis of the ring material, the first and second side regions are obtained by virtually dividing a one half section of the ring material based on a middle of a maximum height of the ring material in the direction of the center axis of the ring material, and a range of the angle is 7 degrees to 40 degrees.

An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

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.

A manufacturing method for a connecting rod includes applying a tensile load to an end portion of the connecting rod as precompression in a cross direction that intersects with a longitudinal direction, the end portion being an longitudinal end portion of the connecting rod and having a through-hole, and fracture splitting the end portion into a rod portion and a cap portion by applying a tensile load to the end portion in the longitudinal direction in a state where the precompression is applied to the end portion.

A method is used to forge an outer joint member of a constant velocity universal joint. Track grooves of the outer and inner joint members each have an arc-shaped ball raceway center line having a curvature center that is not offset in an axial direction with respect to a joint center. The forging method includes performing ironing by press-fitting a cylindrical portion of one end of a shaft portion of a pre-processing material of the outer joint member including the shaft portion and the cylindrical portion into a die hole of a die while a punch set that is radially expandable and contractable is fitted to an inner peripheral surface of the cylindrical portion. The punch set includes punches and a punch base to guide the punches to enable advancing and retreating. Each of the punches has a pair of forming surfaces for forming the adjacent track grooves.

The present invention discloses a method for manufacturing a superior 13Cr tool coupler, which method comprises the following steps: manufacturing a blank; forging the blank; heating the forged blank to 600-700° C. for a stress-relief annealing; quenching; and tempering. The present technical solution can produce a superior 13Cr tool coupler which achieves a mechanic feature of 110 ksi.