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What are the effects of high-frequency welded tube production operations on welding quality?

2021-07-08

1. Welding pressure is one of the main parameters of the welding process. After the two sides of the tube billet are heated to the welding temperature, ordinary metal crystal grains are formed under the action of the extrusion pressure, that is, mutual crystallization produces welding, and the welding pressure affects the strength and toughness of the weld. When the applied welding pressure is small, the welding edge of the metal cannot be completely suppressed, and the residual non-metallic inclusions and metal oxides in the welding seam are not easily discharged due to the low pressure, the welding seam strength is reduced, and the welding strength is easy to crack; when the pressure is too high At this time, most of the metal reaching the welding temperature is squeezed, which not only reduces the strength of the weld, but also produces defects such as excessive internal and external burrs or surfacing. Therefore, in practical applications, the best welding pressure should be obtained according to different specifications.


2. The welding speed is also one of the main parameters in the welding process, which is related to the heating system, the welding seam deformation speed and the mutual crystallization rate. In high-frequency welding, the welding quality improves with the increase in welding speed. This is because the heating time shortens the width of the edge heating zone and shortens the time for forming metal oxides. When the welding speed decreases, not only does the heating zone widen, but the width of the melting zone also changes with the input heat, which causes the internal burrs to become larger. In low-speed welding, the input heat is small and the welding is difficult. If the specified value is not followed Welding is prone to defects.
Therefore, in high-frequency welded tubes, the appropriate welding speed should be selected according to different specifications, and the maximum welding speed allowed by the mechanical equipment and welding equipment of the device is limited.

3. The opening angle refers to the angle between the two sides of the blank tube at the front of the squeeze roll. The opening angle is related to the stability of the firing process and has a great influence on the welding quality. When the opening angle is reduced, the distance between the edges is also reduced, thereby enhancing the proximity effect. Under the same other conditions, the heating temperature of the edge can be increased, thereby increasing the welding speed. In the case that the opening angle is too small, the distance between the confluence point of the squeeze roller and the center line will be extended, causing the edge to not be squeezed at the highest temperature, thereby reducing welding quality and increasing power consumption.