High Frequency Finned Tube Welding Principle
The basis of high frequency welding is to use the two main effects of high frequency current: skin effect and proximity effect. With the help of the skin effect of high-frequency current, high-frequency electrical energy can be concentrated on the surface of the workpiece and the proximity effect can be controlled. The location and range of high frequency current flow. When the high-frequency current is required to be concentrated on a certain part of the workpiece, under the action of the skin effect and the proximity effect, the metal ends of the two adjacent sides will be quickly heated to the melting temperature or welding, and then, under the action of external pressure, the two parts can be firmly welded into a single body.
The pipe welding process with high-frequency welding fins is shown in Figure 1. The steel strip is rolled evenly and steadily on the surface of the steel pipe according to a certain pitch. At the same time, high-frequency current is used as a welding heat source to locally heat the contact surface and waiting area of the steel pipe and steel strip. Welding area, make it melted and weldable state, weld firmly under the application of external force. During the welding process of the spiral fin tube, the steel strip is thin and the current is concentrated, which can easily reach the welding temperature, while the steel tube is thicker and the current is dispersed, which which is not easy to concentrate. The temperature of the steel tube is often lower than the temperature of the steel strip, which affects the quality of welding. If the temperature of the steel pipe increases with increasing power supply power, the heating temperature of the steel belt is often too high and breaks, and the surface temperature of the steel pipe is not enough. Therefore, it is very important to adjust the current distribution of the two and select the appropriate welding parameters. In addition, the high-frequency welding power supplies produced in my country are all high-frequency welding power supplies, and there is no special high-frequency power supply for fin tube welding. Because the impedance of fin tube welding is higher than that of steel tube welding, there is a mismatch between the power source and the load. The problem is that only proper adaptation can increase the power output and prevent power from being consumed by "short circuit". Therefore, improving the characteristics of the high-frequency welding power source and obtaining the best matching of the power source are the prerequisites for ensuring the welding quality of the fin tube.
