Channel Bar Production Line Introduction
Channel steel production lines are industrialized facilities specifically designed for rolling channel steel—a long, strip-shaped steel material with a U-shaped cross-section. They constitute a vital branch of structural steel production lines. Channel steel offers an economical cross-section and excellent mechanical properties, making it widely used in construction structures, machinery manufacturing, vehicle manufacturing, and steel structure engineering (e.g., as load-bearing supports and frame components). Below is a detailed introduction:
Core Functions and Product Features
Product Characteristics: Channel steel features a “U”-shaped (groove-shaped) cross-section composed of a web (vertical central section) and upper/lower flanges (horizontal side sections). Common specifications are denoted as “height × flange width × web thickness” (e.g., 100mm×48mm×5.3mm). Materials are predominantly carbon structural steel (e.g., Q235) or low-alloy steel (e.g., Q355), offering excellent compressive and bending resistance.
Production Objective: Through multi-pass rolling, steel billets are progressively shaped into standard-section channel steel, ensuring dimensional accuracy, perpendicularity between flanges and web, and mechanical properties.
Typical Process Flow
The core of the channel steel production line involves progressively deforming the billet into finished product through the rolling mill's die system, as follows:
Raw Material Preparation
Raw materials consist of continuous cast square billets or hot-rolled billets, with specifications determined by finished channel steel dimensions (e.g., 150mm × 150mm to 300mm × 300mm) and lengths ranging from 6 to 12 meters.
After surface quality inspection (for defects like cracks or folds), the billets are conveyed via loading platforms and roller tables into the heating furnace.
Heating
Billets are heated in a furnace (typically a walking-beam furnace) to 1100-1250°C. This enhances plasticity, reduces rolling resistance, and ensures smooth processing.
Rolling (Core Process)
Rolling is crucial for forming the channel steel cross-section. Through continuous rolling across multiple stands, the billet is progressively shaped into a “U”-shaped profile. This process comprises three stages: roughing, intermediate rolling, and finishing:
Blast Rolling: 3-5 rolling mills use box-shaped or diamond-shaped dies to perform initial reduction in diameter and widening of the billet, removing surface scale to prepare for subsequent forming.
Intermediate Rolling: 4-6 rolling mills progressively shape the channel steel's preliminary form using “open-mold” dies. This stage initiates the formation of the web and flange's basic contours while adjusting dimensional proportions.
Finishing Rolling: 2-4 high-rigidity stands (e.g., universal mills, closed-die mills) use precisely designed dies to finalize the channel steel's cross-sectional dimensions (height, flange width, web thickness). This ensures perpendicularity between flanges and web (preventing “web collapse” or “flange skew”) while controlling surface quality.
Note: Die design is central to channel steel rolling, requiring multiple passes of symmetrical deformation to ensure uniform flange thickness and flat web.
Post-Rolling Treatment
Cooling: Post-rolling channel steel remains at high temperatures (approx. 800-900°C). It is naturally cooled to room temperature via cooling beds (step-type or chain-type) to prevent excessive internal stresses from rapid cooling.
Length Cutting: The cooled channel steel is cut to specified lengths (e.g., 6 m, 9 m, 12 m) using a cold shear. Some production lines employ flying shears for hot-state length cutting to enhance efficiency.
Finishing and Inspection
Straightening: Deformations like bending and twisting are eliminated using section straighteners (multi-roll or pressure straighteners) to ensure straightness and perpendicularity of the cross-section.
Surface Cleaning: Scale and burrs are removed from the surface. Some high-end products undergo shot blasting.
Inspection: Includes dimensional checks (height, flange width, web thickness, etc.), mechanical property tests (tensile, impact), and surface quality inspection (free of cracks, scabs), ensuring compliance with national standards (e.g., GB/T 707).
Packaging and Storage
Qualified channel steel is sorted by specification, bundled using strapping machines, labeled with details such as specification, material grade, and furnace number, then stored in the warehouse or shipped.
Applications of Channel Bars
Channel bars are widely used across various sectors due to their strength and adaptability. Some common applications include:
Construction:
Structural Support: Used as framework, beams, and braces in buildings, bridges, and other large structures.
Roof and Wall Purlins: Provide support for roof sheeting and wall cladding in steel structures.
Framing: Used for door and window frames to provide strong, durable openings.
Stair Stringers and Railings: Form the main supports for staircases and are used in railings.
Manufacturing and Fabrication:
Vehicle Frames: Used in the chassis of trailers and other vehicles.
Machinery Bases: Provide a sturdy foundation for heavy machinery and equipment.
Conveyor Systems: Serve as rails for conveyor systems.
Other Uses:
Fencing and Barriers: Their durability makes them ideal for creating strong barriers and fences.
Signage: Used for mounting large, freestanding signs.
