High frequency welding is a popular method of joining pipes and tubes in many industries. The quality of the weld depends on several factors, including the shape of the end of the pipe or tube being welded, known as the “pipe end,” and the speed at which the welding process is carried out. In this article, we will discuss two more important factors that affect high frequency welding: pipe end shape and welding speed.
Pipe End Shape
The shape of the pipe end, also known as the “pipe end face” or “pipe end profile,” plays a critical role in the quality of the high frequency weld. When welding thick-walled pipes with a thickness of more than 8-10mm, an “I”-shaped pipe end may not be ideal, as it can cause melting of the inner layer of the pipe end and lead to high internal burrs. This can ultimately affect the welding strength of the high frequency welding seam. In such cases, it is better to use a pipe end with an “X” shape, which can help achieve uniform heating and protect the quality of the weld.
The selection of the pipe end shape also affects the size of the weld groove. Thus, when designing a weld joint, proper consideration must be given to the shape of the pipe end to maintain good weld quality. Designing the pipe end properly is essential for controlling the internal quality of the weld and ensuring good manufacturing quality. The design must consider factors like fusion ratio of the parent material, welding space, welding position, and comprehensive economic efficiency.
Welding Speed
The speed at which the welding process is carried out, also known as the welding speed, is another important factor in high frequency welding. Typically, the forming speed of the welding unit is faster than the welding speed. Welding speeds can range from 12 meters per minute (m/min) to 400 m/min, depending on the thickness of the steel plate and the welding method used.
When the welding speed increases, it can help to shorten the heat-affected zone and promote the extrusion of the oxide layer from the molten groove. Conversely, when the welding speed is too low, the heat-affected zone becomes wider, leading to larger burrs, thicker oxide layers, and lower weld quality. However, the welding speed cannot be increased beyond a certain limit because it is limited by the output power of the welding machine.
In China, for example, the welding speed for 2-3mm steel pipes can reach 40 m/min, while for 4-6mm steel pipes, it can reach 25 m/min. For 6-8mm steel pipes, the welding speed is normally 12 m/min, and for pipes with a thickness of 10-16mm, the welding speed can drop below 12 m/min depending on the welding method used.
Conclusion
To ensure high-quality high frequency welding, manufacturers need to consider several factors, like pipe end shape and welding speed. The proper selection of pipe end shape and the optimization of the welding process can result in high-quality welds and improved manufacturing efficiency. Therefore, it is vital to pay close attention to these factors and carry out the welding process with utmost care to achieve the desired results.
