"Fusion of Metals"

Understanding Seam Welding: Techniques and Applications

Seam welding is a specialized welding technique that involves the creation of a bonded joint between metal components, such as steel structural members or panels. This method employs a pair of roller electrodes that move relative to the workpiece to produce a continuous weld seam characterized by overlapping nuggets.

What is Seam Welding?

Seam welding is defined as the process of joining two pieces of metal by applying heat and pressure through the use of roller electrodes. Unlike spot welding, which uses cylindrical electrodes to create individual weld points, seam welding utilizes roller electrodes to create a continuous, sealed weld seam. This technique is particularly effective for assembling lap joints or butt joints, where the weldment is positioned between the two rollers. The rollers apply pressure and rotate, transmitting electrical current to generate heat and form the weld.

Applications of Seam Welding

The seam welding technique finds extensive application across various industries. It is commonly used in the manufacturing of oil drums, cans, radiators, and automotive fuel tanks. Additionally, it plays a crucial role in the production of sealed containers for jet engines, rockets, and missiles, particularly when working with thin metal plates.

Welding Equipment

The primary tools used in seam welding are round roller electrodes, which typically range in diameter from 50 to 600 mm, with a common size being between 180 and 250 mm. These rollers have a thickness of 10 to 20 mm and can have a cylindrical, spherical, or sometimes conical contact surface. The width of the contact surface varies between 3 to 10 mm, depending on the thickness of the workpiece, and the spherical radius can range from 25 to 200 mm.

Cylindrical rollers are generally used for welding various steels and high-temperature alloys, while spherical rollers are preferred for light alloys due to their superior heat dissipation properties. Cooling systems are essential in the welding process; for non-ferrous metals and stainless steel, clean water is typically used, while ordinary steel is often cooled with a borax solution to prevent rust.

Types of Seam Welding Techniques

Seam welding can be categorized into three main types based on the rotation of the rollers and the current feeding method:

1. Continuous Seam Welding: In this method, the roller rotates continuously while the current is also continuously applied to the workpiece. Although this technique can lead to overheating and electrode wear, it is sometimes used in high-speed applications, such as in the barrel manufacturing industry, where a solder joint is formed with each half cycle of alternating current.

2. Intermittent Seam Welding: This technique involves continuous roller rotation with intermittent current application. The resulting weld consists of overlapping nuggets, and the cooling periods during current interruption enhance the lifespan of the roller and improve weld quality by reducing the heat-affected zone and workpiece deformation. This method is widely utilized for welding various steels, superalloys, and titanium alloys with thicknesses of less than 1.5 mm.

3. Step Seam Welding: In this method, the roller rotates intermittently, and the current is applied when the workpiece is stationary. This approach allows for improved heat dissipation and pressure application, leading to enhanced welding quality. Step seam welding is particularly effective for aluminum and magnesium alloys, as well as high-temperature alloys, although the availability of AC welding machines for this method is limited.

Conclusion

Seam welding is a versatile and effective welding method that plays a critical role in various manufacturing processes. By understanding the different techniques and applications, manufacturers can select the most suitable method for their specific needs, ensuring high-quality welds and improved product performance. As technology advances, the development of more sophisticated welding equipment and techniques will continue to enhance the capabilities of seam welding in various industries.