Re Bar Production Line Detail
Re bar production lines are specialized industrial facilities designed to manufacture ribbed steel bars (commonly known as rebar). As a specialized segment within bar production lines, their output is primarily used for reinforcing steel in concrete structures such as buildings, bridges, and hydraulic engineering projects. The transverse and longitudinal ribs on the bar's surface enhance bond strength with concrete, thereby improving structural stability. Below is a detailed overview:
Core Functions and Characteristics of Re Bar Production Line
Product Characteristics: Rebar features a circular cross-section with two longitudinal ribs and uniformly spaced transverse ribs along its length. Common specifications range from 6mm to 50mm in diameter, primarily manufactured from hot-rolled ribbed steel bars like HRB400 or HRB500. It exhibits high strength, excellent ductility, and superior bond strength with concrete.
Production Objective: Form regular rib patterns on the surface of round bars through rolling processes (rib spacing, height, etc., must comply with national standards), while ensuring dimensional accuracy, mechanical properties, and surface quality of the steel bars.
Typical Process Flow
The production flow of a ribbed steel bar line is similar to that of a bar rolling mill, but incorporates the critical rib forming step during rolling. The specific process is as follows:
Raw Material Preparation
The raw material is continuous cast square billets (e.g., 150mm×150mm, 180mm×180mm) with lengths of 6-12 meters. The material is selected as carbon structural steel or low-alloy steel based on finished product requirements.
After inspection (to ensure no surface cracks, inclusions, or other defects), the billets are fed into the heating furnace via a loading platform and conveyor rollers.
Heating
The billets are heated in a step-heating furnace or push-type furnace to 1050-1200°C, achieving the temperature required for plastic deformation and reducing rolling resistance.
Rolling (Core Process)
Blast Rolling: 6-8 rolling stands reduce the heated billet into larger intermediate billets (e.g., 50-80mm diameter) using box or diamond-shaped dies for initial deformation and surface scale removal.
Intermediate Rolling: 6-10 stands further reduce diameter and refine cross-sectional shape to prepare for finishing. Some stands employ alternating horizontal-vertical arrangements to prevent workpiece torsion.
Finishing Rolling: 4-6 high-rigidity stands (e.g., short-stress-line mills) use specially designed threaded rolls to form transverse and longitudinal ribs on the surface while controlling final diameters (e.g., φ12mm, φ25mm). Rolling speeds reach 15-25m/s.
Note: Thread dies are critical, as their shape determines rib height, spacing, and profile. Strict compliance with national standards (e.g., GB/T 1499.2) is required.
Post-Rolling Processing
Controlled Cooling: Rapid cooling via water-through cooling devices (water tanks) regulates the steel bar's phase transformation process, achieving uniform microstructure (e.g., ferrite + pearlite) to ensure mechanical properties (yield strength, tensile strength, etc.).
Flying Shear Cutting: During bar movement, flying shears cut to preset lengths (e.g., 9 m, 12 m), replacing traditional cold shears to enhance efficiency.
Finishing and Inspection
Straightening: Multi-roll straighteners eliminate bending deformation, ensuring straightness (deflection ≤4 mm per meter).
Surface Cleaning: Removes residual scale from the surface (some products require cleaning after natural cooling on a cooling bed).
Inspection: Includes dimensional checks (diameter, rib height, spacing), mechanical property tests (tensile, bending), and surface quality inspection (no cracks, folds), ensuring compliance with standards.
Packaging and Storage
Qualified threaded steel is bundled by specification (diameter, length) into bundles (approx. 2-3 tons per bundle). After spray-printing identification (specification, material grade, furnace number, etc.), it is stored in the warehouse or shipped.
