In the production of structural tubes, consistent mechanical properties and reliable weldability are critical for downstream applications in construction, machinery and steel structures. To meet these requirements, Yuantuo has developed an induction quenching and tempering line specifically designed for square, rectangular and round tubes.

The line uses electromagnetic induction heating to bring the tube to the required quenching and tempering temperature, followed by water spray cooling and controlled reheating. With a Siemens PLC control system, the complete process is fully automated and easy to operate, helping tube manufacturers improve product quality while reducing energy consumption.

Application Range and Main Technical Parameters

• Tube size range

  • Square tubes: 80 × 80 – 200 × 200 mm

  • Round tubes: Ø108 – Ø219 mm

  • Rectangular tubes and profiles within the corresponding size range

• Wall thickness: 3 – 8 mm

• Material: carbon steel and alloy steel

• Line speed: 10 – 35 m/min (depending on size and grade)

• Induction heating power: approx. 750 kW

• Induction frequency: around 3,000 Hz

• Control system: Siemens PLC with HMI operator panel

• Temperature measurement: infrared pyrometer for online monitoring

These parameters can be customized according to the customer’s product mix and production requirements.

Process Layout of the Quenching and Tempering Line

The mechanical and process layout of the line is designed for continuous, stable operation:

1. Overhead crane loading to the storage platform

2. Automatic bar/tube feeding system

3. Infeed roller conveyor

4. Induction heating system for quenching

5. Infrared temperature measurement and monitoring

6. Quench zone with water spray system

7. Outlet roller conveyor after quenching

8. Transfer to tempering section

9. Induction tempering system

10. Infrared temperature measurement in the tempering zone

11. Final cooling and outlet roller conveyor

12. Discharge and collecting racks

This layout ensures smooth material flow from loading to final collection, minimizing manual handling and allowing integration into existing tube production lines.

Design Features and Advantages

1.Energy-efficient induction power supply
The line uses a water-cooled, thyristor-controlled medium-frequency power supply. The high energy efficiency of induction heating, combined with optimized coil design, helps reduce overall power consumption and supports cleaner production.

2.V-type roller design for square and rectangular tubes
For square and rectangular tubes, the line is equipped with inclined V-type rollers. This design improves tube guidance, reduces radial run-out and helps maintain straightness during high-temperature processing.

3.Fast heating with minimal surface oxidation
Medium-frequency induction heating provides rapid and uniform heating of the tube wall. Together with controlled rotation during heating and quenching/tempering, this reduces surface oxidation and helps achieve good straightness after heat treatment.

4.Consistent mechanical properties
After quenching and tempering, the tubes obtain a uniform hardness distribution, homogeneous microstructure and good toughness and impact resistance, which are important for demanding structural and mechanical applications.

5.Process traceability through PLC and HMI
The Siemens PLC control system with touch-screen HMI can record and store key process parameters during quenching and tempering, such as heating power, temperature data, line speed and water flow. This allows users to trace production batches and optimize recipes over time.

With its combination of automation, process stability and energy-efficient operation, Yuantuo’s induction quenching and tempering line has become a reliable solution for tube manufacturers seeking to upgrade their heat treatment capabilities.