A system and method of making a forged part. The method may include forming a workpiece in a first die unit that may be disposed in a first press, transferring the workpiece to a tooth forming die unit that may be disposed in a second press, and forming the workpiece into the forged part by forming a set of teeth on the workpiece with the tooth forming die unit.

A manufacturing method and apparatus for gears for a speed change device. The gears having a large end and a small end forming a reverse-tapered tooth part on an outer circumference thereof, spline teeth of an intermediate material having the small end provided in a rim of the large end thereof, a plurality of dies having a radial shape and an inclination angle to a gear axial line and slidably holding to an inclined axial line on a holding member are slid from outside of the radiation direction toward the center by a pushing cam mechanism, thereby pushing the reverse-tapered blade part formed at the leading end of the die, the spline teeth are formed in the reverse-tapered tooth part, and the die is slid by an extracting mechanism from the center of the radiation direction toward the outside along the inclined axial line.

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.

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.

In order to minimize the sliding friction occurring between the locking parts, that is, between the pawl and the rotary latch of a motor vehicle lock, it is advantageous if, during the machining process, the different latch surfaces of both locking parts are provided with a punched contour and with a contour having a oblique machining groove. Machining grooves are formed, in particular on the latch surface thereof, after stamping the pawl. Defined shapes of oblique channels and/or machining grooves are produced, for example, by milling out the machining grooves. The oblique machining grooves are produced at a defined angle and guarantee that the straight channels on the rotary latch only have a few overlapping points with the oblique grooves, if both locking parts come into contact with each other.

Mating bevel gears generally include a pinion gear having a body that rotates about an axis and a side gear having a body that rotates about an axis that intersects the axis of the pinion gear. Pinion gear teeth of the pinion gear have a side that defines a curvature with an involute section through which a pitch line extends and a parabolic shape between the pinion gear teeth. Side gear teeth of the side gear have a side that defines a curvature with an involute section through which a pitch line extends and a parabolic shape between the side gear teeth. The curvatures on the pinion and the side gear teeth cooperatively define a controlled relative radius of curvature section except where the involute sections are located. The controlled relative radius of curvature section defines a sum of values of radius of curvature at a point of contact between the curvatures of the pinion gear teeth and the side gear teeth. The sum has a constant or decreasing value.

A method for manufacturing a gear includes providing a rim gear, a hub and a core wherein the core is annular and has a core forging temperature below a hot hardness temperature of the rim gear and the hub. The rim gear and the hub are rotated about an axis relative to the core. During the relative rotation, the rim gear and the hub are in contact with the core to generate friction heat to raise an interface temperature of the core to the core forging temperature. The hub is driven into the core to upset a first portion of the core into an outer annular groove defined in a first faying surface of the hub. The rim gear is driven over the core to upset a second portion of the core into an inner annular groove defined in a second faying surface of the rim gear.

A hollow rack bar and a method of manufacturing the hollow rack bar are provided. The hollow rack bar includes a hollow blank pipe portion having a uniform wall thickness, and a rack toothed portion. The rack toothed portion includes teeth, a flat portion having a flat surface and arranged side by side with the teeth in a direction along a center axis of the blank pipe portion, and a slanted portion provided at an end of the flat portion with respect to a direction perpendicular to the center axis and arranged to be lower than the flat portion. A length of the slanted portion projected on a straight line perpendicular to the center axis and parallel to the surface of the flat portion is longer than zero and equal to or shorter than the wall thickness of the blank pipe portion.

A forging apparatus carries out a method of manufacturing a gear having external teeth on an outer circumferential wall surface thereof and internal teeth on an inner circumferential wall surface thereof. First, an internal tooth forming die is inserted through a through hole defined in a workpiece. Next, a pressing die is caused to abut against the workpiece, and an external tooth machining die finishes the external teeth while preventing a support die from being lowered under action of damping mechanisms. Thereafter, a pressing die presses the workpiece to apply a load in excess of a preset load for the damping mechanisms. The support die is then lowered to lower the workpiece along the internal tooth forming die. At this time, the internal teeth are formed on the inner circumferential wall surface of the workpiece.

An upper die and a lower die are brought together to perform a sizing work on a roughly forged part of a primary forged article within a die cavity defined between the upper and lower dies. The lower die has a vertical through-hole directly communicated with the die cavity, and a punch is relatively movably received in the vertical through-hole in such a manner as to define jointly with the vertical through-hole an annular material flow passage. During the sizing process, a material of the roughly forge part is forced against a peripheral surface of the die cavity and excess material is allowed to flow into the annular material flow passage.