What Is a Wire Rod Coiler in Rolling Mills?

What Is a Wire Rod Coiler?

In a wire rod rolling mill, finished wire must be converted into compact coils for transportation, storage, and downstream processing.

A wire rod coiler is the equipment responsible for winding hot rolled wire into coils with controlled shape and dimensions.

From a structural standpoint, traditional coilers are mainly divided into:

• Axial feeding (vertical / pot-type or “bell-type”) coilers
• Radial feeding coilers

However, in modern high-speed wire rod rolling lines, conventional coilers are largely replaced by a more advanced system:

Laying head + controlled cooling + coil collecting system

This evolution is driven by increasing rolling speeds, larger coil weights, and stricter metallurgical requirements.

What Is a Laying Head?

A laying head is the key device in modern wire rod production used to transform a straight, high-speed wire into uniform spiral coils.

Working Principle

• The wire rod enters the laying head axially
• It is then discharged tangentially through a rotating laying pipe
• The rotation forms continuous helical loops
• These loops are deposited onto a moving conveyor (chain or roller type)

This process creates loose coils, which are ideal for:

• Uniform cooling
• Controlled metallurgical transformation
• Prevention of coil entanglement

Why Laying Heads Are Essential

Modern mills often use:

• 45° no-twist rolling blocks
• Rolling speeds exceeding 100 m/s
• Coil weights up to 5 tons

Under these conditions, traditional coiling is insufficient. The laying head enables:

• Stable coil formation at high speed
• Improved heat dissipation
• Consistent mechanical properties of the final product

Laying Head + Controlled Cooling Process

After the laying head forms loose coils, the process continues as follows:

1. Coil deposition
   Spiral loops are laid onto a conveyor system
2. Transport + air cooling
   1. Coils move along a roller or chain conveyor
   2. Forced air cooling provides a controlled cooling rate
   3. This acts as an online heat treatment process
3. Metallurgical control
   By adjusting cooling intensity, the system ensures:
   1. Metallographic structure
   2. Target mechanical properties
4. Coil collection
   At the end of the conveyor:
   1. Coils are gathered into compact bundles
   2. Then transferred to binding/packing equipment

Key Technical Features (From a 150,000 t/y Wire Rod Project)

Below are representative, practical parameters from an actual project specification, useful for engineering reference:

Laying Head

• Installation: Horizontal, inclined ~15° downward
• Function: Form and distribute coils onto cooling conveyor
• Structure:
  • Rotating shaft + laying pipe
  • Driven by DC variable-speed motor + bevel gears
• Cooling design:
  • Internal guide pipe with water cooling jacket
  • Protects bearings from high temperature transfer
• Maintenance:
  • Protective housing with hydraulic opening mechanism
• Dynamic performance:
  • Dynamic balancing accuracy: ≥ G2.5
  • Test speed: ~3000 rpm
  • Vibration limit: ≤ 4 mm/s

Typical Parameters:

• Wire diameter: Φ5.5–8 mm
• Coil diameter: ~Φ1080 mm
• Supplied material speed: 20–50 m/s
• Motor speed: 600–1200 rpm

Controlled Cooling Conveyor

• Function:
  • controlled cooling of loose coils
  • transport coils to collection station
•  Structure:
  • Heat-resistant roller tables (ductile iron / welded steel)
  • Variable-speed drive via AC motor + reducer + chain
  • Adjustable roller sections for coil shaping
  • Air cooling chambers beneath rollers
  • Coil centering and guiding devices
• Key Features:
  • Roller speed: 25–1.5 m/s
  • Allowable bearing highest temperature of roller table: ~900°C