How Are High Frequency Welded Spiral Fin Tubes Made?

How Are High Frequency Welded Spiral Fin Tubes Made?

The manufacturing process of high-frequency welded spiral fin tubes requires precise control at every step, from base tube selection, fin forming to high-frequency welding and quality inspection.

Steel strips are resistant to high temperatures and aluminum strips have excellent thermal conductivity. They are rolled and wound to form a tight structure, and then welded with high-frequency current to ensure strength. Finally, they are strictly tested to ensure performance and safety.

The manufacturing process of high-frequency welded spiral fin tubes mainly includes the following key steps:

Raw material preparation for high-frequency welded spiral fin tubes

Base tube selection

According to the use environment and performance requirements, select steel pipes of suitable materials and specifications as base pipes, such as carbon steel, stainless steel, alloy steel, etc.

The surface quality and dimensional accuracy of the base tube have an important influence on the performance and quality of the fin tube. Therefore, the quality of the base tube must be strictly controlled to ensure that its surface is smooth and has no obvious defects, and the tube diameter and wall thickness meet the design requirements.

Fin material selection

Common fin materials are steel strips or aluminum strips. Steel strips are strong and resistant to high temperatures, and are suitable for harsh environments such as high temperature and high pressure; aluminum strips have good thermal conductivity and corrosion resistance, and can play an advantage in some occasions with high weight and heat dissipation requirements.

The thickness, width and material properties of the fin material also need to be selected and inspected according to the specific application.

High-frequency welding spiral fin tube fin forming

Steel strip or aluminum strip rolling

The selected steel strip or aluminum strip is rolled through the rolling equipment to achieve the required thickness and width. During the rolling process, the rolling speed, pressure and other parameters should be controlled to ensure the dimensional accuracy and surface quality of the fin material, and prevent problems such as uneven thickness and surface scratches.

Fin spiral winding

Use special winding equipment to wind the rolled fin material on the surface of the base tube at a certain spiral angle and spacing. During the winding process, the winding speed and tension need to be accurately controlled to ensure that the fins are tightly and evenly wound on the base tube to avoid loose fins, overlaps or inconsistent spacing.

According to the product specification requirements, the spiral angle should be adjusted to meet different heat transfer and fluid mechanics performance requirements.

High-frequency welding of spiral finned tubes

High-frequency current application

The base tube with the fins wrapped is sent into the high-frequency welding equipment, and the high-frequency current is applied through the induction coil. The high-frequency current will produce skin effect and proximity effect on the contact surface of the base tube and the fin, so that the surface is quickly heated to a plastic state or a molten state.

Pressure welding

While heating, a certain pressure is applied to the fins and the base tube through a mechanical device, so that the fins in a plastic or molten state are tightly combined with the surface of the base tube to form a firm weld.

The parameters of welding pressure, welding speed and high-frequency current need to be optimized and adjusted according to the material and specifications of the base tube and fins to ensure the welding quality and ensure that the welding rate and weld strength meet the requirements.

High-frequency welding spiral finned tube welding quality inspection

Appearance inspection

Mainly check the appearance quality of the finned tube, including whether the fins are neatly wound, whether the welds are uniform and continuous, and whether there are defects such as leaks, cold welds, and weld penetration. For some minor defects on the surface, such as partial incomplete welds or a few burrs on the edge of the fin, manual trimming can be performed.

Nondestructive testing

Use nondestructive testing methods such as ultrasonic testing and magnetic particle testing to test the internal quality of the weld to check whether there are internal cracks, pores, slag inclusions and other defects.

Nondestructive testing can accurately detect hidden quality problems without destroying the fin tube, ensuring reliable product quality.

Post-processing of high-frequency welded spiral fin tubes

Cutting and sizing

According to actual use requirements, the welded fin tubes are cut according to the specified length to ensure that the length of each fin tube meets the design requirements. During the cutting process, pay attention to the flatness and verticality of the cut to avoid the situation where the cut is tilted or there are too many burrs.

Surface treatment:

The surface of the fin tube is treated with rust removal and oil removal to improve its corrosion resistance and surface quality. Common surface treatment methods include pickling, phosphating, sandblasting, etc. For some occasions with special requirements, anti-corrosion coating or electroplating may be required to further improve the corrosion resistance and service life of the finned tube.

High frequency welded spiral finned tube performance test

Heat transfer performance test

The heat transfer performance of the finned tube is tested through the experimental device, and its heat transfer coefficient, thermal resistance and other parameters under different working conditions are measured to evaluate whether it meets the design requirements and performance indicators of actual application.

Heat transfer performance test is an important part of testing the quality of finned tube products, which can provide a basis for the optimal design and application of products.

Pressure test

Pressure test the finned tube, including static pressure test and water pressure test, to test its sealing and strength under the specified pressure.

Pressure test can simulate the pressure environment of the finned tube in actual work to ensure that there will be no safety problems such as leakage or rupture during operation.