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Method of welding high strength steel with medium frequency inverter spot welder [DCS25]

Jan 07,2024

Both High-strength low-alloy steel spot and projection welding require much higher current than normal steel plate welding, usually using short-time high-current pulse mode.

Either spot welding or projection welding requires much higher current on the welding of high strength steel plates that of ordinary steel plates. Short time high current sharp pulse mode is often used for the welding of high strength steel workpieces.

The common problem in the welding course with medium frequency inverter welding machine is as the following.

When welding high strength steel plate and nut, the nut projections get collapsed and melted completely, but the steel plate does not get melted. Or, the nut and steel plate get welded together, however, the nut gets burned out of color or even the nut thread gets damaged.

What should we do if we want to have better use of medium frequency inverter spot welder to carry on spot welding or projection welding to the high-strength steel nuts ?

We know that the discharge form of medium frequency inverter spot welding machine is a similar trapezoidal square wave. The discharge time is controllable. Because of the difference of control mode and energy form, the setting and actual discharge time of medium frequency inverter spot welder is higher than that of energy storage spot welder.

Under the condition that the performance of the welder can guarantee the current climbing rate, it is necessary to set a welding parameter which is shorter than the ordinary welding time (about 20ms) and higher about 1/3 welding current than ordinary welding current. Generally it also follows the welding method of high current and short time. At the same time, increase the welding pressure to increase the contact resistance at the solder joint, note that the pressure can not be adjusted too high. Thus, the projection welding of high strength steel nuts can be carried out well.

Therefore, when using medium frequency inverter spot welder to weld high-strength steel, welding current capacity and climbing rate is very important. Have such a basis to simulate the waveform of energy storage spot welding machine and then do a good job of spot or projection welding.