Direct Forming Square Tube Mill for Efficient Production

With the continuous growth of the construction, machinery manufacturing, and steel structure industries, the market demand for square and rectangular tubes is steadily increasing. As specialized steel tube forming equipment, these mills have become essential for modern steel tube manufacturers due to their stable forming quality and high production efficiency.

I. Introduction to Square Tube Mill

A Square Tube Mill is a steel tube forming production line designed for the continuous manufacturing of square tubes and rectangular tubes. Using steel strips such as carbon steel, stainless steel, and galvanized steel as raw materials, the equipment achieves high-efficiency, large-scale production through continuous roll forming and welding processes.

Overall, a square tube mill is a highly integrated automated production line that combines mechanical, electrical, hydraulic, and automatic control technologies. Its core function is to transform steel coils into finished square or rectangular tubes through a series of processes, including uncoiling, leveling, forming, welding, cooling, sizing, and cutting, ensuring that the final products meet required standards for length, dimensional accuracy, and mechanical performance.

II. Working Principle

The core working principle of a square tube mill lies in the combination of continuous roll forming and high-frequency welding technology.

After uncoiling and leveling, the steel strip enters the forming section. Under the gradual compression and guidance of multiple forming rolls, the strip edges move closer and form an open tube profile. Subsequently, a high-frequency welding unit rapidly heats and fuses the strip edges under high temperature and pressure, creating a strong longitudinal weld seam. After welding, the tube passes through sizing and straightening units to ensure accurate outer dimensions, straightness, and surface quality of the square tube.

III. Production Process Flow

A typical square tube mill production process includes the following stages:

1. Uncoiling and Leveling (Preparation Stage)

Uncoiler: Supports and smoothly unwinds the steel coil, ensuring continuous material feeding.

Leveler: Uses multiple precision rollers to eliminate strip curvature and internal stress, ensuring flat and stable material before forming.

2. Forming

After entering the forming section, the steel strip is gradually and uniformly bent into a tube profile through multiple forming passes (typically 8–16 passes) arranged in a rational sequence, creating optimal conditions for subsequent welding.

3. Welding

High-frequency welding (HFW) technology is commonly applied. When the open edges of the tube are tightly pressed together, high-frequency current instantly heats and fuses the metal edges, forming a continuous and robust longitudinal weld seam.

4. Sizing and Straightening

After welding, the tube passes through sizing and straightening units to further correct outer dimensions and geometric accuracy, ensuring precise side length, right-angle accuracy, diagonal consistency, and overall straightness.

5. Online Cutting and Run-Out

Flying Cut-Off Saw: Performs dynamic, on-line length cutting according to preset parameters while the tube is continuously moving.

Run-Out Table: Transfers, collects, stacks, or bundles finished tubes.

The entire production process features a high level of automation and stable operation, making it particularly suitable for continuous and large-scale production.

IV. Process Characteristics

Square tube mills exhibit several notable process characteristics in actual production:

Continuous Forming: From steel strip to finished tube, the entire process is continuous and uninterrupted, ensuring high production efficiency.

High-Frequency Welding (HFW): Fast welding speed, small heat-affected zone, and high weld strength, with performance close to that of the base material.

High-Precision Sizing: Effectively guarantees right-angle accuracy, diagonal consistency, and excellent straightness of square tubes.

High Production Flexibility: By changing certain rolls or tooling, a single production line can cover multiple sizes of square and rectangular tubes.

V. Application Areas

Square and rectangular tubes produced by square tube mills are widely used across various industries, including but not limited to:

Building structures and steel structure engineering

Machiery manufacturing and equipment frames

Furniture manufacturing and decorative applications

Automotive, construction machinery, and storage systems

Solar mounting systems, guardrails, and industrial pipelines

Thanks to their excellent load-bearing capacity and processing adaptability, square and rectangular tubes play a vital role in both industrial and civil applications.

VI. General Advantages of Square Tube Mills

Compared with traditional production methods, modern square tube mills offer the following common advantages:

High Frming Accuracy: Stable dimensions and consistent product quality

High Production Efficiency: Continuous production suitable for mass manufacturing

StrongAdaptability: Capable of producing multiple sizes of square and rectangular tubes

High Automation Level: Reduced manual intervention and lower production costs

Stable and Reliable Operation: Rational structure, easy maintenance, and long service life

VII. Advantages of Aogang Square Tube Mill

1. Direct Forming Technology for Higher Efficiency and Energy Savings

Aogang square tube mills adopt advanced direct forming technology, allowing steel strips to be formed directly into square or rectangular tubes without the traditional “round forming followed by reshaping” process. This significantly simplifies the production route, improves efficiency, and reduces overall energy consumption and operating costs.

2. Reduced Material Consumption and Lower Production Costs

By improving material utilization through direct forming technology, raw material consumption can be reduced by approximately 5% compared with conventional processes, effectively lowering production costs and improving return on investment.

3. High-Precision Corner Control for Superior Product Quality

The equipment precisely controls the forming radius and angle of all four corners, resulting in a more uniform appearance and higher structural strength, meeting the requirements of high-standard applications in construction, machinery, and precision structures.

4. Fast Size Changeover for Enhanced Production Flexibility

Aogang square tube mills support multi-size and small-batch production. With intelligent tooling and parameter adjustment systems, rapid size changeovers can be achieved, minimizing downtime and significantly improving production flexibility and market responsiveness.

5. Intelligent Control System with High Automation

Equipped with an advanced PLC control system and automated adjustment solutions, the production line operates stably from uncoiling to finished product output, reducing operational complexity while enhancing consistency and reliability.

6. Significant Investment Cost Efficiency

A single production line can cover multiple product sizes, reducing the number of rolls required and inventory pressure. This lowers equipment investment and floor space requirements, helping customers build efficient and economical production lines.

7. Multi-Industry Applications and Material Compatibility

The equipment is suitable for producing square and rectangular tubes made from MS, GI, and high-strength steels, serving a wide range of industries such as construction, furniture, machinery manufacturing, and energy.

With over 20 years of experience in tube mill equipment R&D and manufacturing, Aogang is supported by professional design, manufacturing, and installation teams. Certified by CE, SGS, and other international standards, Aogang has successfully delivered and installed more than 2,000 production lines worldwide, continuously providing customers with stable and reliable square tube production solutions.