ERW Tube Mill Flattener: Why Thick Steel Strip Needs Flattening

Jul . 06, 2026 11:53

📌 What Is a Flattener?

A Flattener is an optional strip preparation machine installed in the entry section of an ERW tube mill. Its main function is to remove coil set and improve the flatness of the steel strip before it enters the forming mill.

The machine mainly consists of pinch rolls and leveling rolls. The pinch rolls feed the strip continuously, while the leveling rolls repeatedly bend the strip to release internal stress and eliminate coil curvature, ensuring stable forming and welding performance.

⚙️ Main Components

🔹 Pinch Rolls

Grip and feed the steel strip smoothly.
Maintain stable strip feeding into the leveling section.

🔹 Leveling Rolls

Repeatedly bend the strip in opposite directions.
Remove coil set and improve strip flatness.
Reduce internal stress before forming.

🔄 Working Principle

The steel strip is first driven by the pinch rolls into the machine. It then passes through multiple leveling rolls, where it is repeatedly bent upward and downward. This reverse bending process gradually removes the strip's natural coil curvature and releases residual stress.

The flattened strip then enters the forming mill with improved flatness, helping achieve stable forming, accurate edge alignment, and consistent welding quality.

📍 Where Is It Installed?

The Flattener is installed after the Uncoiler and before the Shear & Welder in an ERW tube mill.

Typical production line:

➡️ Uncoiler → Flattener → Shear & Welder → Accumulator → Forming Mill → HF Welder → Sizing → Flying Saw

✅ When Is a Flattener Recommended?

A Flattener is an optional machine in an ERW tube mill.

It is generally recommended when:

✔️ Strip thickness is above 5 mm
✔️ Processing high-strength steel
✔️ Better strip flatness is required
✔️ Higher welding and forming stability is expected

For thinner steel strips, the material is usually flexible enough to enter the forming mill directly without additional flattening.

🎯 Why Choose AIS Machinery?

At AIS Machinery, we supply complete ERW tube mill solutions tailored to different pipe sizes and strip thicknesses.

For heavy-gauge production lines, we can configure a suitable Flattener and Leveler to improve strip preparation and ensure reliable downstream production. Our engineering team selects the appropriate machine specifications based on your strip width, thickness, and production requirements.

flattener

❓Frequently Asked Questions

Q1: Is a Flattener and Leveler required for every tube mill?

No. It is an optional machine. For strip thicknesses below approximately 5 mm, many production lines operate without it. For thicker materials, it is generally recommended to achieve better strip flatness and forming stability.

Q2: What is the difference between pinch rolls and leveler rolls?

Pinch rolls mainly feed and grip the steel strip, while leveler rolls perform the actual leveling process by repeatedly bending the strip to remove coil set.

Q3: What materials can it process?

It is suitable for carbon steel strips commonly used in ERW pipe manufacturing. The machine configuration is selected according to strip width, thickness, yield strength, and production capacity.

Pervious

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