A processing method of NPR steel rebar coil, wherein the NPR steel rebar is cold processed and has a diameter of less than 14 mm, the NPR steel rebar 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 20%;
- the processing method comprises the following steps:
- a I-shaped placing step L20:
- fixing one end of a rebar rack, and performing head-to-tail welding of the steel rebar at a front end of the steel rebar without stopping;
- an uncoiling step L30:
- providing a drawing force to a I-shaped de-coiler along a travel direction of steel rebar to preliminarily flatten the steel rebar, and synchronizing the I-shaped de-coiler with a wire drawing machine through intelligent control equipment to deliver the steel rebar synchronously for subsequent steps;
- a flattening step L40:
- repeatedly bending the steel rebar to remove a stress in the steel rebar by a wheel-rolling flattening method, so as to flatten the steel rebar without scratch on its surface;
- a pointing step L50:
- correcting or removing surface shape defects of a head part of the steel rebar by a pointing process, during each start of head threading process in the production line;
- a butt welding step L60:
- matching a diameter of the steel rebar by controlling current using PLC numerical control technology, welding the steel rebar according to the time required for steel rebar welding and current for welding, and automatically removing burrs on a surface of the steel rebar after welding is completed;
- a hydraulic head-pushing step L70:
- pushing the head part of the steel rebar to pass through a smooth mold, and setting a length of the head part of the steel rebar passing through the smooth mold according to requirements of the wire drawing machine;
- a cold drawn smoothing step L80:
- performing diameter modification and finishing of NPR steel rebar to make a diameter of a generatrix uniform;
- a grit blasting step L90:
- automatically adjusting output of steel grit according to a diameter and surface requirements of the steel rebar to be processed, and processing oxide scales, surface defects on the surface of hot-rolled NPR steel rebar and lubricating powders of the smooth mold inline, by using intelligent numerical control technology and communicating with a master control equipment;
- an in-situ inline annealing step L10:
- performing in-situ inline heating and annealing of the steel rebar;
- an air-cooled tempering step L11:
- cooling high temperature steel rebar wire inline by air-cooling;
- a coiling step L12:
- high-speed coiling the steel rebar with residual temperature or residual heat, and performing automatic feeding, chucking, automatic head and tail cutting, and automatic unloading;
- a placing step L13:
- uncoiling and placing the steel rebar coil after subjecting to shaping and annealing heat treatment;
- a flattening step L14:
- eliminating an internal stress of the steel rebar using a method of multi-wheel crossed 360-degree curve rolling and straightening;
- a cold drawn spiral ribbing step L15:
- forming spiral ribs on the steel rebar by means of roller die cold rolling;
- a straightening step L16:
- performing fine adjustment based on flattening, using a method of multi-wheel crossed or horizontal straightening;
- and
- a coiling step L17:
- coiling and bundling without stopping inline production.