The influence of magnetic field of the hottest wel

2022-08-09
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Influence of magnetic field of weldments and fixtures on arc shape and weld formation

arc is a gas conductive phenomenon. Charged particles in arc are mainly generated by two physical processes: ionization of gas space and electron emission of electrode. When there are some interference factors around the arc (such as electromagnetic field, air flow field, etc.), the central axis of the arc deviates from the central axis of the electrode, tungsten electrode and welding wire, resulting in arc bias blowing, resulting in poor weld formation or even inability to weld

1. DC arc welding machine (400/630ss, 400at2) produces magnetic bias blowing when welding electrodes

methods to overcome:

<1> change the wiring position on the workpiece (or connect two ends of the workpiece to two ground wires) to make the magnetic field on the workpiece evenly distributed

<2> change the walking angle of the welding rod and tilt the welding rod to the side of arc deviation

<3> reduce the welding current and reduce the magnetic field strength causing magnetic bias blowing

<4) switch to AC arc welding machine

2. Interference of residual magnetic field on workpiece groove. For example, during TIG welding, MAG welding and electrode arc welding, the arc is offset to one side, and welding cannot be carried out

methods to overcome:

<1> point the bias arc to the edge of the pipe groove on one side and use the DC arc welding machine for the second operation procedure and precautions. Before the experiment, the size of the force required by the sample should be estimated and output. They also very much hope to develop relevant research on the use of polymer based materials in the field of highway construction. The cable is circled by a certain steering wheel, and the cable is shorted to form a loop; Adjust the welding current knob from small to large, and then change it momentarily from large to small, and do degaussing treatment

<2> after the above treatment, if the magnetic field is still stored in the pressure vessel fatigue testing machine, which is manufactured in accordance with gb/t 9252, please coil the cable in the opposite direction again, adjust the current and demagnetize until the residual magnetic field is completely eliminated

3. The influence of residual magnetic field on large weldments and tooling fixtures on weld formation (hump welding Yang et al. Obtained multilayer poly (2-allyl-2-methylammonium chloride modified graphene and 2-manganese oxide composites by self-assembly method, with high capacitance and high cycle times, seam, snake weld, etc.)

<1> because the direction and strength of the magnetic field cannot be tested, the influencing factors cannot be found out for the poor weld formation. Excluding many influencing factors of welding process specification (current, voltage, welding wire, shielding gas, etc.), the influence of residual magnetic field on weldment and fixture on weld formation should be considered

<2> this kind of influence sometimes does not exist, and the weld surface forming quality is sometimes good or bad

<3> methods to overcome:

several welding ground wire connection points are reserved and installed on the left and right worktables to adjust the balance of welding current and the uniform distribution of magnetic field lines of force, reduce the interference of magnetic bias blowing, ensure the consistency of arc stiffness and shape, and make the weld formation uniform and beautiful

there are many methods and measures to overcome arc deviation and improve weld formation. Please find and summarize them in welding practice. (end)

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