In the heat treatment of steel tubes and profiles, square and rectangular tubes have long been considered a challenging category due to their unique geometry. Traditional conveying methods—such as angled roller tables designed to induce pipe rotation—are suitable for round tubes, but often lead to inconsistent heating, corner overheating, misalignment, and deformation when applied to square sections.

Based on extensive project experience, Yuantuo Electromechanical Equipment Manufacturing Co., Ltd. has developed and implemented a more reliable solution: a Dual-Pinch-Roll Synchronous Drive System specifically designed for square tubes, rectangular tubes, and similar non-round profiles. This technology effectively resolves common industry issues related to stability, uniformity, and precision throughout quenching and tempering processes.

1. Industry Challenge: Square Tubes Are Difficult to Heat Uniformly

Unlike round tubes, the flat surfaces and sharp corners of square tubes receive magnetic field distribution unevenly during induction heating. Conventional rotation-based conveying systems can lead to:

• Unstable rotation

• Higher temperatures at the edges compared to flat surfaces

• Increased risk of tube misalignment

• Greater deformation during quenching due to internal stress concentration

These issues directly affect product hardness consistency, mechanical properties, and process repeatability.

2. Yuantuo’s Dual-Pinch-Roll Drive Ensures Stable Feeding and Uniform Heating

Yuantuo’s solution adopts a double pinch roll system that grips the tube securely and drives it forward synchronously, delivering several key advantages:

• Straight, Stable Forward Feeding (No Rotation Required)

Square tubes remain firmly clamped and advance steadily through the heating section without relying on rotational motion—eliminating the usual causes of runout and oscillation.

• More Suitable for Square Tube Heating: “Stable Forward Motion Without Rotation”

Custom-designed square induction coils and edge magnetic-field compensation allow the tube to reach uniform temperature across all four sides, even without rotation.

• Reduced Risk of Bending During Quenching

Controlled straight-line movement ensures lower internal-stress imbalance, significantly reducing longitudinal bending or twisting.

• Fully Automated Temperature and Process Control

Integrated systems include:

• PLC-based control

• Infrared real-time temperature feedback

• Automatic feeding and discharge
  This creates a stable and repeatable quenching & tempering process.

3. Custom Induction Coils and Magnetic Circuit Optimization

To meet diverse tube sizes and heat-treatment requirements, Yuantuo applies a modular furnace design including:

• Custom square/rectangular induction coils

• Optimized magnetic yokes

• Corner-field compensation structures

• Closed-loop temperature control

• Automated power adjustment

These measures keep the temperature deviation within ±5–10 °C, meeting demanding mechanical-property requirements.

4. Wide Application Range for Non-Round Profiles

This solution is applicable not only to square tubes, but also to:

• Rectangular tubes

• Structural sections

• Flat bars, channels, and other shaped profiles

Configurations can be customized according to throughput, hardness specifications, material grade, and production rhythm.

5. Proven Performance Across Multiple Customer Sites

Yuantuo’s dual-pinch-roll heat treatment system has been successfully deployed in multiple tube manufacturing plants, demonstrating:

• More uniform heating

• Stable hardness consistency

• Reduced surface defects and corner overheating

• Lower deformation rates

• Improved automation and production efficiency

Square-tube heat treatment requires equipment engineered specifically for non-round geometries. Yuantuo’s dual-pinch-roll synchronous drive system—combined with custom induction coil design and optimized magnetic-field control—provides a mature and stable solution trusted by steel manufacturers worldwide.

Yuantuo remains committed to delivering reliable, energy-efficient, and highly automated induction heat-treatment systems for the global metals industry.