A method of manufacturing a rack bar includes: a rolling die abutment step of bringing a pair of rolling dies into abutment against an intermediate portion of a workpiece; and a ball screw groove forming step of forming a ball screw groove in the workpiece by moving the workpiece relative to the pair of rolling dies so that a region of the workpiece against which the pair of rolling dies is brought into abutment is moved from the intermediate portion toward a first end portion of the workpiece.

The present invention is directed to an axial thread rolling process that utilizes a thread rolling head that includes a clutch, that prevents full disengagement of the clutch during thread rolling, and that reverses the direction of rotation used for thread rolling to escape a threaded workpiece from the thread rolling head.

The present invention is directed to an axial thread rolling process that utilizes a thread rolling head that includes a clutch, that prevents full disengagement of the clutch during thread rolling, and that reverses the direction of rotation used for thread rolling to escape a threaded workpiece from the thread rolling head.

A thread rolling tool for rolling or repairing a thread has a tool body, a profiled roller, and at least one counter roller. The profiled roller and the at least one counter roller are mounted on the tool body. Preferably, at least one of the profiled roller and the at least one counter roller is mounted so that it is axially displaceable. The profiled roller has a profiled roller profile that has a pitch.

This invention provides a method for rolling an external pipe thread, a rolling head and device thereof. A rolling wheel carries out a thread rolling, wherein the thread rolling starts from a thread tail of the external pipe thread and moves towards a thread head of the external pipe thread, thereby completing the thread rolling. The rolling head of the invention comprises at least one rolling wheel arranged along a circumference, a corresponding rolling wheel axle and a corresponding rolling wheel seat; the rolling wheel is rotatably fixed to the rolling wheel seat via the rolling wheel axle; and the rolling wheel is provided with a pipe thread forming part having a thread length less than an effective thread length of the external pipe thread to be rolled. The rolling head of the invention also comprises a radial regulating device that can realize dynamic rolling and real-time whole-process regulation of radial position of the rolling wheel for the purpose of forming the taper as required by rolling process. The invention also provides rolling device including aforesaid rolling head. Solutions as provided by this invention are expected to guard against deformation to the pipe end during rolling, significantly save materials for hollowed cylindrical blank, and improve the rate of finished products.

A turning and thread-rolling machine with a pre-compression device includes a fixing base on which the pre-compression device, a fixing mechanism, a guiding base, a processing mechanism assembly, and a control unit are provided, wherein the pre-compression device includes a carrier and at least two cold-rolling heads in order to form by compression a pre-compressed annular groove in a portion of an unprocessed rebar that is adjacent to one end thereof, and, under the control of the control unit, the fixing mechanism clamps the rebar, and the guiding base displaces the processing mechanism assembly to the end of the rebar to perform turning and thread rolling sequentially, thereby processing the end of the rebar into a coupling end. The pre-compressed annular groove facilitates on-site inspection of thread quality and prevents the thread-rolling dies in the processing mechanism assembly from contact with, and hence damage by, the ribs on the rebar.

A turning and thread-rolling machine with a pre-compression device includes a fixing base on which the pre-compression device, a fixing mechanism, a guiding base, a processing mechanism assembly, and a control unit are provided, wherein the pre-compression device includes a carrier and at least two cold-rolling heads in order to form by compression a pre-compressed annular groove in a portion of an unprocessed rebar that is adjacent to one end thereof, and, under the control of the control unit, the fixing mechanism clamps the rebar, and the guiding base displaces the processing mechanism assembly to the end of the rebar to perform turning and thread rolling sequentially, thereby processing the end of the rebar into a coupling end. The pre-compressed annular groove facilitates on-site inspection of thread quality and prevents the thread-rolling dies in the processing mechanism assembly from contact with, and hence damage by, the ribs on the rebar.

A thread rolling head includes a bearing housing, in which at least two profile rollers, preferably at least three, are each rotatably mounted on an eccentric shaft. A shank is coupled to the housing, and adjacent profile rollers delimit an insertion section into which a workpiece can be longitudinally inserted. The bearing housing includes two housing parts rotatable relative to each other to change the spacing between the profile rollers. An adjustment element interacts with one of the two housing parts and can rotate about the longitudinal axis thereof. Rotation of the adjustment element in a first direction causes rotation of the two housing parts in a third rotational direction, while its rotation in the second direction causes rotation of the housing parts in a fourth rotational direction counter to the third rotational direction. A display apparatus displays a change of the spacing between the profile rollers.

The present invention is to provide an automatic steel bar coupling head making machine including a positioning mechanism, a transverse moving mechanism, a longitudinal moving mechanism, a processing mechanism assembly and a control mechanism, wherein, when a steel bar is positioned between two fixtures of the positioning mechanism and an end of the steel bar presses against a positioning detection rod of the processing mechanism assembly, the processing mechanism assembly sends a start signal to the control mechanism and, upon receipt of the start signal, the control mechanism drives the positioning mechanism, the transverse moving mechanism, the longitudinal moving mechanism and the processing mechanism assembly, for enabling the two fixtures to clamp the steel bar and then enabling the processing mechanism assembly to sequentially perform a first turning, a second turning and a thread rolling on peripheral edge of the steel bar adjacent to the end of the steel bar.

The invention relates to a thread rolling tool for rolling or repairing a thread with a tool body (12) a profiled roller (36) that is mounted on the tool body (12), and at least one counter roller (14.1) that has a counter roller rotational axis (D.sub.14.1) and is mounted on the tool body (12). According to the invention, it is recommended that the profiled roller (36) and/or the at least one counter roller (14) is mounted so that it is axially displaceable.