來源：http://www.railway-signal.com/ 發布時間：2021-12-07 瀏覽次數：
In the welding process of welding robot, when the included angle between electrode and welding direction is 90 degrees, the arc is concentrated and the molten pool temperature is high; Small angle, dispersed arc and low bath temperature. For example, when making 12mm flat weld back sealing layer, the angle of welding rod shall be controlled at 50-70 degrees to reduce the temperature of molten pool and avoid back welding bump or surge.
Secondly, the arc striking time of welding robot system should be strictly controlled. The arc breaking frequency and arc burning time directly affect the bath temperature. Due to the thin pipe wall, the ability to withstand arc heat is limited. If the arc breaking frequency is slowed down and the weld pool temperature is reduced, it is easy to produce shrinkage. Therefore, the arc combustion time can only be used to control the weld pool temperature to avoid high internal welds or weld beads in the pipeline.
Generally, the welding robot should select the welding current and electrode diameter according to the position of welding gap and welding level. When welding, the welding current and electrode diameter are larger, and the vertical and horizontal positions are smaller. Only in this way can the temperature of the molten pool be controlled more easily to form the weld.
The welding robot adopts a built-in welding clamp, and the welding transformer is installed behind the welding clamp, so the transformer should be as small as possible. For transformers with small capacity, AC power supply frequency of 50Hz can be used, while for transformers with large capacity, inverter technology has been used to change AC power supply frequency from 50Hz to AC 600-700hz, thus reducing the volume of the transformer. Once the voltage is changed, it can be directly welded with 600-700hz AC or DC after secondary rectification. The welding parameters are set by timer, as shown in Figure 1b. The new timer has been micro calculated, so the robot control cabinet can directly control the timer without additional interface. The welding tongs of spot welding robot usually use pneumatic welding tongs, and the gap between the two electrodes of pneumatic welding tongs is generally only two levels. In addition, once the electrode pressure is established, it cannot be changed at will. In recent years, a new type of servo electric spot welding gun has emerged. The opening and closing of the welding gun is driven by the servo motor and fed back by the encoder. The opening of the welding gun can be arbitrarily selected and preset according to the actual needs.
According to previous experience, when the welding robot uses circular strip steel, the molten pool temperature is higher than that of crescent strip steel, and the temperature of crescent strip steel is higher than that of sawtooth strip steel. With the oscillation and pause amplitude on both sides of the groove, the molten pool temperature can be effectively controlled.
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