how the currrent frequency and input power affect the high frequency welding
There are three main effects of high frequency current in high frequency welding: 1.
Skin effect: the welding current density is concentrated on the surface of the belt end to achieve a high heating effect. 2.
Proximity Effect: pull the welding current to the nearest central belt to improve heating efficiency and lateral heating uniformity of the belt. 3.
Electric repulsive force: exclude the molten liquid steel in the heating area from the surface of the steel strip.
Frequency has a great influence on high frequency welding, partly because high frequency affects the current distribution inside the plate.
The selection of high and low frequencies mainly affects the size of the weld heat affected zone.
In terms of welding efficiency, a relatively high frequency is preferable.
High frequency current of 100 KHZ, can be through the process of ferritic steel 0.
1mm, while only 0 is passed at 400 KHZ.
04mm, that is, for the current density distribution on the surface of the steel plate, it is nearly 2.
5 times higher than the former.
In production practice, in welding carbon-
Steel generally can choose the frequency of 350 KHZ to 450 KHZ;
When welding alloy steel such as thick steel plates of more than 10mm, some relatively low frequencies of 50 KHZ to 150 KHZ can be selected, because alloy steel contains chromium, zinc, copper, aluminum and other elements, they will differ from steel due to skin effects.
Many high abroad now
Most manufacturers of frequency conversion equipment adopt new technologies of solid state and high frequency.
After setting the frequency range, according to the material thickness, unit speed and other conditions, the frequency will be automatically tracked and adjusted during welding. B.
The input power is very important to control the input power when performing high frequency welding.
When the input power is too small, the heat of the pipe tank is insufficient and the welding temperature is not reached, which will cause poor welding, unwelding, welding slag and other phenomena.
When the input power is too large, the stability of the welding is affected, and the heating temperature on the surface of the pipe slot is significantly higher than the temperature required for welding, causing serious splash, air holes, slag, and other defects.
This defect is called a burnt defect.
The input power of high frequency welding shall be determined by the wall thickness and molding speed.
For different molding methods, different unit equipment and different material steel grades, we need to summarize from the first production line of high-frequency process equipment to prepare ourselves.