1. The effect of welding current. It is clear from the recipe that the current has a greater effect on the production of heat than resistance and time. Therefore, it is a parameter that must be strictly controlled in the spot welding process. The key causes of current shift are grid voltage vibration and impedance shift of the AC welding machine secondary circuit. The impedance shift is due to a change in the geometry of the circuit or to the introduction of a different amount of magnetic metal in the secondary circuit. With regard to the DC welder, the impedance shift in the secondary circuit has no apparent effect on the current.
In addition to the total welding current, the current density has a significant effect on the heating. The shunting of the welding point and the increase of the electrode contact area or the convex surface size in the case of convex welding will reduce the current density and the welding heat reception heat, thus making the reception intensity significantly lower.
2. The effect of welding time. To ensure the size of the molten core and the strength of the welded joint, the welding time and the welding current may complement each other. In order to obtain a positive strength welded joint, we may wish to choose a high current and short light (strong current), or a low current and long time (weak current). Depending on the function of the metal, the thickness and the power of the welder, the conditions for choosing strong current and long time (weak current and long time) remain weak. However, there is still an upper and lower limit for the current and time required for different functions and thicknesses of the metal, beyond which no passage through the nucleus will result.
3. The effect of electrode pressure. The electrode pressure has a significant effect on the total resistance between the two electrodes. As the electrode pressure increases, the resistance significantly decreases. At this point, although the welding current increases slightly, it does not affect the decrease in heat production due to the decrease in resistance. Therefore, the solder joint strength always decreases with increasing electrode pressure. Increasing the electrode pressure is accompanied by increasing the welding current or extending the welding time to fill the effect of reduced resistance, and it may be desirable to keep the welded joint strength fixed. The choice of this welding condition is beneficial to improve the stability of the weld joint strength. If the electrode pressure is too low, it will cause spatter and reduce the strength of the welded joint.
4. The effect of electrode raw material function. The form and raw material of the electrode have a significant effect on the fusion nucleus, because the contact area of the electrode determines the current density. The resistivity and thermal conductivity of the raw material of the electrode are related to the occurrence and loss of heat. As the electrode head deforms and wears, the contact area increases and the strength of the welded joint decreases.
