Bar Bundling Machine for Rolling Mill | BDNA-800 Automatic Bundling System

Introduction

In modern rolling mills, the final product quality is not determined only by rolling precision, but also by the stability and reliability of the finishing and bundling system.

For rebar and round bar production lines, the performance of the automatic bar bundling machine directly affects:

• Bundle tightness

• Transportation safety

• Product appearance consistency

• Customer acceptance

The BDNA-800 Automatic Bar Bundling Machine, developed by Guangdong Borton Intelligent Equipment Co., Ltd., is designed for Φ10–Φ50mm rebars with bundle weights from 1500–5000 kg and a bundling cycle time ≤8 seconds.

This technical article summarizes the structural optimization and PLC logic improvements implemented to enhance operational stability under high-capacity rolling mill conditions.

1. Equipment Overview – BDNA-800 Automatic Bar Bundling Machine

Main Technical Parameters

• Applicable bar size: Φ10–Φ50 mm

• Bundle weight: 1500–5000 kg

• Maximum bundle diameter: 550 mm

• Bundling cycle: ≤8 s per strap

• Bundling force: ≥9000 N

• Hydraulic pressure: approx. 10 MPa

• Control system: Siemens PLC (automatic / manual mode)

• Motor power: 11 kW

• Track system diameter: Φ800 mm

The machine adopts a 45° disc-type twisting head, which provides:

• More balanced mechanical stress

• Higher twisting stability

• Reduced spare part wear

• Full interchangeability of key components

2. Working Principle of the Bundling Cycle

The standard automatic cycle consists of:

1. Bundle arrives at bundling position

2. Bundling head descends

3. Bundle former clamps the bundle

4. Wire feeding

5. Reverse feeding for tightening

6. Dual-end clamping

7. Twisting and cutting

8. Former release

9. Head return

10. Signal to move bundle

Total cycle time: approximately 8 seconds.

3. Operational Challenges Identified in High-Capacity Rolling Mills

During long-term operation in bar rolling mills, the Technical Center identified several key issues:

3.1 Feeding Wheel Locking (Wire Brake Jamming)

In double-strapping applications (especially for export bundles):

• Wire tower height limitation

• Insufficient wire length during second bundling

• Forced pulling under brake lock condition

This led to:

• Accelerated brake wear

• Reduced twisting quality

• Loose bundles after long-distance transport

3.2 Lack of Automatic Double-Strap Program

For export or port material, head and tail reinforcement requires double strapping (up to 10 straps per bundle).

Originally:

• Manual intervention required

• Cycle instability

• Risk of missed strapping

3.3 No End Alignment Device

Due to friction during conveyor movement:

• Bundle ends became misaligned

• Poor visual appearance

• Reduced packaging quality perception

3.4 Insufficient Strength of A/B Zone Stop Plate

Original stop plate thickness: 7 mm.

Long-term stress resulted in:

• Deformation

• Misalignment

• Scratching or bending of finished bars

4. Systematic Optimization Measures Implemented

Borton Technical Center carried out a comprehensive upgrade program.

4.1 Twisting Enhancement and PLC Optimization

• Twisting turns increased from 3 to 5

• Extended secondary bundling timing

• Optimized wire tension control logic

• Reduced entry roller opening angle

• Installed bundle holding arm between bundling units

Results:

• Reduced twisting head wear

• Improved bundle tightness

• Lower loose bundle rate

4.2 Development of Automatic Double-Strap Function

The original PLC English program was restructured:

• Single-strapping function block

• Double-strapping function block

• HMI selection interface

Now supports:

• Fully automatic double bundling

• Seamless mode switching

• Stable production rhythm

Significantly improved efficiency and consistency.

4.3 Installation of Pneumatic End Alignment Device

Using compressed air cylinders:

• High-speed reciprocating impact

• End alignment correction

• Stable air supply via main line with buffer tank

Result:

• Uniform bundle ends

• Improved packaging appearance

4.4 Reinforcement of Stop Plate Structure

• Thickness upgraded from 7 mm to 20 mm

• 30 mm welded nut reinforcement

• Enlarged air passage diameter

• Relocated vulnerable joints

Result:

• Improved structural rigidity

• Eliminated scratching risk

• Extended service life

5. Performance Verification After Optimization

Field validation under continuous production:

Bundling cycle time

≤8 seconds per strap

Twisting failure rate

<2% per 1000 twisting operations

Bundling force

≥9000 N

Equipment availability

≥99% under two-shift production

Under annual production capacity of 1,000,000 tons, stable operation was achieved.

6. Technical Significance for Modern Rolling Mills

The improvement proves that a high-performance bar bundling machine depends on:

• Mechanical structure optimization

• Hydraulic matching

• PLC logic control

• Auxiliary mechanism integration

Rather than isolated component upgrades.

Future development direction:

• Higher automation level

• Reduced manual intervention

• Lower failure rate

• Modular structural design

• Extended spare part lifetime

Conclusion

Through systematic structural reinforcement and control system optimization, the BDNA-800 Automatic Bar Bundling Machine has evolved from stable operation to high-reliability continuous production performance.

Borton Intelligent Equipment remains committed to delivering:

• Reliable rolling mill finishing solutions

• Advanced bar bundling systems

• Sustainable long-term operational value

For modern steel plants worldwide.

Application in Middle East and Southeast Asia Rolling Mills

BDNA-800 automatic bar bundling machines have been optimized for high-temperature, high-humidity and continuous production environments commonly found in Middle East and Southeast Asia steel plants.

Stable hydraulic performance, reinforced structure and double strapping automation ensure reliable operation under export-oriented production requirements.

In high-capacity rolling mills (1,000,000 tons/year production lines), stable automatic bundling systems are essential to maintain product consistency and transport safety.

FAQ – Automatic Bar Bundling Machine

Q1: What causes loose bundling in rolling mills?
A: Loose bundling is usually caused by insufficient wire tension, twisting head wear or feeding brake locking.

Q2: How to improve twisting stability in bar bundling machines?
A: Increasing twisting turns, optimizing PLC logic and stabilizing hydraulic pressure can significantly reduce failure rate.

Q3: What is the failure rate of BDNA-800?
A: Less than 2% per 1000 twisting operations under continuous production conditions.

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