Tension wound fin tube is a high-efficiency heat exchange element manufactured through mechanical winding process. Its core is to spirally wind metal strips on the outer surface of the base tube under specific conditions to form fin structures that enhance heat exchange. This process is mainly divided into two technical routes: cold winding and hot winding, and the selection depends on material characteristics and product performance requirements.

 

The tension winding process includes three key steps:

1. Base Tube Pretreatment: Clean the surface of the base tube to remove oil stains and oxides. Sandblasting is often used to form a rough surface to improve bonding strength.

2. Winding Forming: Fix the pretreated base tube on the main shaft of the winding machine. After the metal strip is pre-bent through the forming die, it is spirally wound on the rotating base tube with a preset pitch (typically 1-10mm). The cold winding process applies a radial pressure of 15-25kN through pressure wheels to ensure the strip closely adheres to the base tube and undergoes plastic deformation to achieve mechanical interlocking.

3. Fixing and Strengthening: Perform strengthening and fixing after winding. Industrial large-diameter fin tubes are reinforced with intermittent spot welding using micro-plasma welding, with a weld spot diameter of approximately 2-3mm; civil small radiators adopt rolling lock edge technology to ensure long-term stability of fins under vibration and thermal stress.

 

Divided into two processes according to processing temperature:

- Cold Winding Process: Carried out at room temperature, using mechanical pressure to cause plastic deformation of the fin and base tube surface and mutual embedding to form mechanical interlocking. It avoids damage to material properties caused by high temperature, with low contact thermal resistance of approximately 0.0005-0.001 m²·K/W.

- Hot Winding Process: Suitable for high-temperature working conditions. First, heat the fin strip to a specific temperature (200-300℃ for carbon steel, 150-200℃ for aluminum alloy) to reduce yield strength, then perform winding. After winding, high-frequency welding is usually used for reinforcement, and the weld strength can reach more than 180MPa, which can better withstand thermal expansion and contraction stress.

 

- Advantages: High process flexibility, can adapt to different materials (such as steel, aluminum, copper) and fin spacing requirements by changing strips and adjusting parameters; relatively low equipment investment, high production efficiency, with a single-line daily capacity of 1000-1500 meters.

- Limitations: The fin and base tube are mainly mechanically bonded, and the bonding strength is lower than metallurgical bonding, resulting in relatively high contact thermal resistance (approximately 0.1-0.2 m²·K/W). Under continuous temperature fluctuations or vibration conditions, there is a risk of fin loosening, and the service life is usually designed to be 5-8 years.

 

Due to its high cost performance and flexible production, tension wound fin tubes are widely used in scenarios where heat exchange efficiency and long-term durability requirements are not extremely stringent, such as household wall-hung boiler radiators, small commercial air conditioning units, and low-temperature heat exchange sections in industrial heat exchange equipment.

 

In summary, tension winding is an important forming process for fin tubes, and the technical selection needs to comprehensively consider factors such as operating conditions, material combinations, and cost-effectiveness.