A steering rack meshes with a pinion rotatably driven by the input shaft of a steering gear constituting an automotive steering device. The steering rack is provided with a an axially extending rod part of round cross section, and a plurality of rack teeth formed on a radial one side surface of an axial portion of the rod part, the rack teeth meshing with the pinion. At least one dummy tooth is formed in portions that are axial parts of the rod part and are adjacent to both axial sides of the plurality of rack teeth. The dummy tooth has a tooth height less than the rack teeth and does not mesh with the pinion.

A method for producing a rack for a steering gear may involve providing a toothed segment and a shaft segment aligned on a longitudinal axis and connecting the segments by axial joining faces by friction welding at a welding joint. For friction welding, the joining faces may be brought into frictional contact by an initial friction force, the segments may be rotated relative to one another, the joining faces may be mutually compressed by way of a contact pressure force until a predefined joining path has been reached by way of a welding force 10 to 20 times the initial friction force, thermal input friction may be performed by an input force 5 to 12 times the initial friction force, and the segments may be moved toward one another in an axial direction by the predefined joining path. The segments may be held in position without friction.

A rack for a steering gear may include a toothed portion that has a toothing extending along a longitudinal axis, and a generally cylinder-segment-shaped back opposite the toothing and having a back radius. A method for producing such a rack may involve forming a cylindrical blank with an unmachined radius between a toothed die part having a toothed mold clearance and a back die part having a back mold clearance in a die cavity. The die may have a generally cylinder-segment-shape. In an open position of the die, the blank may be inserted between the toothed mold clearance and the back mold clearance. The toothed die part and the back die part in a forging stroke for closing the cavity may then be moved in a closing direction to a closed position. The back radius of the back mold clearance may be larger than the unmachined radius of the blank.

A support apparatus for supporting a steering rack forged in a forging die, comprising a gripper to grip the shank of the rack, a lost-motion mechanism supporting the gripper and permitting limited movement in the direction of closing of the forging die, and a side-shift mechanism to move the gripper sideways. The lost-motion mechanism abuts the die assembly as the forging die closes thereby positioning the gripper to grip the shank of the steering rack during the final closing travel of the forging die. The gripper then lifts the steering rack as the forging die opens. The side-shift mechanism then moves the gripped steering rack sideways.

A steering rack includes a rack shaft (10), a plurality of rack teeth (11a) formed on the rack shaft and each having a tooth trace inclined with respect to a first direction perpendicular to an axial direction of the rack shaft, and a dummy tooth (33a) aligned with the rack teeth and formed on the rack shaft. The dummy tooth (33a) is non-uniformly formed in a second direction parallel to the tooth trace of the rack tooth (11a).

A rack may include a toothed portion having a toothing, and a shaft portion having a threaded portion with a coaxial thread that has a thread length in an axial direction of a longitudinal axis. Separate segments comprising at least one in each case bar-shaped toothed segment and one shaft segment are provided, are aligned on the longitudinal axis, and are connected to one another at a joint. A method for producing the rack may involve providing a shaft raw material piece having a piece length that is a multiple of a shaft segment length, generating a thread that is continuous in a longitudinal direction on the shaft raw material piece across a multiple of the thread length to produce a threaded semi-finished product, cutting to length a threaded segment from the threaded semi-finished product, providing a toothed segment, and joining the threaded segment to the toothed segment.

A steering rack (11a) meshes with a pinion rotatably driven by the input shaft (6) of a steering gear (5) constituting an automotive steering device. The steering rack (11a) is provided with a an axially extending rod part (15) of round cross section, and a plurality of rack teeth (16) formed on a radial one side surface of an axial portion of the rod part (15), the rack teeth (16) meshing with the pinion. At least one dummy tooth (42) is formed in portions that are axial parts of the rod part (15) and are adjacent to both axial sides of the plurality of rack teeth (16). The dummy tooth (42) has a tooth height less than the rack teeth (16) and does not mesh with the pinion.

There is provided a manufacturing method of a rack shaft which includes rack teeth formed on an axial portion thereof. A specific stroke is constant at least at a predetermined axial position of the rack teeth. The specific stroke corresponding to a movement amount of the rack shaft per rotation of a pinion shaft including pinion teeth to be meshed with the rack teeth. The rack teeth are formed by forging processing, and after heat treatment is performed, a finish processing is performed only on an axial center portion in which the specific stroke is constant in the rack teeth.

A steering rack includes a rack shaft (10), a plurality of rack teeth (11a) formed on the rack shaft and each having a tooth trace inclined with respect to a first direction perpendicular to an axial direction of the rack shaft, and a dummy tooth (33a) aligned with the rack teeth and formed on the rack shaft. The dummy tooth (33a) is non-uniformly formed in a second direction parallel to the tooth trace of the rack tooth (11a).

In a rack bar and a steering device using the same, an endmost tooth bottom for reducing a stress exerted on a first forging die during die forging of a rack tooth molding part is formed on the endmost side of a plurality of tooth bottoms. Specifically, the endmost tooth bottom is formed so that a depth thereof is less than a depth of an ordinary tooth bottom by a difference. This reduces an amount of flow of a material of the rack bar during formation of the endmost tooth bottom by an amount commensurate with the difference. As a result, the stress exerted on the first forging die can be reduced, and occurrence of heat checking in the first forging die can be suppressed.