A processing method of NPR steel rebar rod is disclosed. The NPR steel rebar is cold processed and has a yield strength of 800˜950 MPa, a tensile strength of 900˜1100 MPa, and a percentage elongation at maximum force of not less than 10˜40%. The processing method comprises the following steps: a I-shaped placing step L20, an uncoiling step L30, a flattening step L40, a butt welding step L50, a sandblasting step L60, a straightening step L70, a pointing step L80, a hydraulic head-pushing step L90, a cold drawn spiral ribbing step L10, a straight forward continuous wire drawing and traction step L11, a pre-straightening step L12, a fine straightening step L13, and a cutting-off step L14. The processing method can meet the automatic intelligent production requirements of NPR steel rebar, cold rolled spiral NPR steel rebar, and pre-stressed NPR steel rebar.

A processing method of NPR steel rebar rod is disclosed. The NPR steel rebar is cold processed and has a yield strength of 800˜950 MPa, a tensile strength of 900˜1100 MPa, and a percentage elongation at maximum force of not less than 10˜40%. The processing method comprises the following steps: a I-shaped placing step L20, an uncoiling step L30, a flattening step L40, a butt welding step L50, a sandblasting step L60, a straightening step L70, a pointing step L80, a hydraulic head-pushing step L90, a cold drawn spiral ribbing step L10, a straight forward continuous wire drawing and traction step L11, a pre-straightening step L12, a fine straightening step L13, and a cutting-off step L14. The processing method can meet the automatic intelligent production requirements of NPR steel rebar, cold rolled spiral NPR steel rebar, and pre-stressed NPR steel rebar.

A method for determining the stamping quality of profiled bar includes steps of: a) upstream of the rolling stand performing shaping, the initial speed V.sub.A of the starting product is determined and the initial diameter D.sub.A or initial cross-sectional area F.sub.A are determined contactlessly. b) After the rolling stand, the final speed V.sub.E of the end product is measured and the diameter D.sub.E or area F.sub.E of a virtual enveloping shell for the end product is determined contactlessly. c) The diameter D.sub.N of a virtual, round end product is determined contactlessly as D.sub.N=square root of (D.sub.A.sup.2*V.sub.A/V.sub.E) and/or the average cross-sectional area F.sub.NE of the end product (2) is determined contactlessly as F.sub.NE=F.sub.A*V.sub.A/V.sub.E. d1) The characteristic stamping variable PKG is calculated, and the characteristic stamping variable PKG is compared with a pre-set setpoint value PKG.sub.set. A device for carrying out the method is also provided.

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.

Embodiments of the invention comprise forming a billet from molten steel and hot rolling the billet to reduce the cross sectional area of the billet. Thereafter, the billet is hot rolled into a lead pass bar having a cross-sectional area comprising a reduced width dimension located adjacent to the center longitudinal axis of the bar. In one embodiment of the invention, the billet can be formed into a lead pass bar having a cross-sectional area in the shape of an hourglass or peanut by feeding the billet through a first set of rolls. After the lead pass bar is formed, it is passed through a second set of rolls in order to form the substantially continuous threaded rebar without longitudinal ribs. The cross-sectional area of the lead pass bar helps to produce a substantially continuous threaded rebar product without longitudinal ribs using standard rebar manufacturing tooling and equipment.

A method of making steel fibers, preferably for use as a concrete additive, and for the supply thereof in making steel fiber concrete, characterized in that to form the steel fibers (2) first a sheet-metal strip (1) is notched either on one face or both faces so as to form steel-fiber wires (4) that are initially connected together by webs (5), and that further, for subsequently converting the webs (5) into thin easily mutually separable separation webs forming separation surfaces that are fracture-rough and low in burring upon separation, the steel-fiber strip is subjected to a flexing process in which each web (5) is subjected to multiple bending deformations about its longitudinal axis in such a way that incipient cracks are produced at the webs (5) due to fatigue fracture and thus the separation webs are produced.