Bar Production Line Introduction
The bar production line is an industrialized production system specifically designed to process metal billets (primarily steel billets, but also including non-ferrous metal billets such as copper and aluminum) into bars with fixed cross-sectional shapes—such as round, square, or hexagonal—through continuous rolling and finishing processes. As critical equipment in metal pressure processing, it is widely used in the steel and non-ferrous metal industries. Its output—bars—serve as fundamental raw materials for sectors including machinery manufacturing, construction, automotive, aerospace, and power generation.
Core Functions and Features
Continuous Production: From billet heating to finished product storage, all stages are interconnected via roller tables and conveying equipment, enabling continuous operation with high production efficiency (achieving hourly output ranging from tens to hundreds of tons).
Multi-pass Rolling Deformation: Through sequential rolling by multiple stands, the billet's cross-sectional dimensions are progressively reduced and its shape adjusted, ultimately producing bars that meet specifications (e.g., round bars with diameters ranging from 10mm to 150mm, square bars with side lengths from 16mm to 100mm).
Product Diversity: Capable of producing bars in various materials (carbon steel, alloy steel, stainless steel, etc.), cross-sections (round, square, hexagonal, special shapes), and specifications to meet diverse requirements.
Key Equipment
A complete bar production line is a modular system made up of several key machines:
Mixers: For blending ingredients.
Forming Machines: Such as roller presses or extruders to create the bar shape.
Cooling Tunnels: To solidify the bars or coatings.
Cutting Machines: Guillotines or slitters for precise cutting.
Enrobing and Decorating Equipment (Optional): For applying coatings and toppings.
Packaging Machines: To wrap and seal the finished bars.
Typical Process Flow
Raw Material Preparation
Raw materials include continuous cast billets and hot-rolled billets, typically measuring 120mm×120mm to 200mm×200mm with lengths of 6-12 meters.
After inspection (for surface defects like cracks or inclusions), the billets are conveyed via loading platforms and roller conveyors into the heating furnace.
Heating
The billets are heated in a furnace (e.g., a walking beam furnace) to 1000-1250°C (adjusted per steel grade) to achieve optimal plasticity and reduce rolling resistance.
Rolling
Blast Rolling: The heated billet is rolled into a larger-section intermediate slab (e.g., 50-100 mm diameter) using 6-8 stand two-high rolling mills with box or diamond-shaped rolls for initial deformation.
Intermediate Rolling: Further reduces cross-section and adjusts dimensional accuracy. Typically employs 6-10 stands, with some using alternating horizontal-vertical arrangements (to prevent workpiece torsion).
Finish Rolling: Final control of bar dimensional accuracy (tolerances as tight as ±0.1mm) and surface quality. Utilizes high-rigidity mills (e.g., short-stress-line mills) with rolling speeds reaching 15-30m/s.
Post-Rolling Processing
Controlled Cooling: Rapid cooling via water-through cooling systems to control steel phase transformations, optimizing microstructure and mechanical properties (e.g., enhancing strength, improving toughness). Flying shear cutting: Cuts bars to specified lengths (e.g., 6m, 9m, 12m) while in motion, replacing conventional cold shears to enhance efficiency.
Finishing
Straightening: Eliminates bar curvature using multi-roll straighteners to ensure straightness (deflection ≤1mm/m).
Surface Cleaning: Remove scale (e.g., shot blasting, acid pickling); select high-end products require polishing.
Inspection: Conduct dimensional measurements (diameter, edge length), mechanical property testing (tensile, hardness), and non-destructive testing (eddy current, ultrasonic) to ensure quality.
Bundling and Storage
Qualified bars are bundled by specification, marked, and stored in inventory or shipped.
Key Equipment
Heating Furnace: Ensures uniform billet heating while minimizing oxidation and burn loss.
Rolling Mill: Core units include roughing, intermediate, and finishing mills, determining bar dimensional accuracy and surface quality.
Flying shear: Enables dynamic cut-to-length shearing, adapting to high-speed rolling.
Straightening machine: Improves bar straightness to meet subsequent processing requirements.
The technical level of a bar production line directly impacts product quality (e.g., dimensional accuracy, surface finish, mechanical properties) and production efficiency. Modern lines integrate automated control (e.g., PLC, computer optimization) and online inspection technologies to achieve efficient, stable, and high-quality production.
