What Is The Reason For Virtual Welding In SMT Processing?
The essence of virtual welding is that the surface temperature of the welded joint is too low when welding, the size of the nugget is too small or even reaches the degree of melting, but it has reached the plastic state, and after rolling, it has almost no bonding, so it seems that it is welded. of. In fact, it is not fully integrated.
Analyze the causes and steps of virtual welding in patch processing:
1. First check the surface of the welded joint for any rust, oil and other impurities, or uneven and poor contact, which will increase the contact resistance, reduce the current, and the temperature of the welded joint surface is not enough.
2. Check if the welding amount of the weld is normal, and whether the amount of overlap on the driving side is reduced or cracked. The reduction in the amount of overlap causes the joint area of the front and rear steel strips to be too small, so that the total force surface is reduced and cannot withstand large tensions. In particular, the crack on the driving side causes stress concentration, which causes the crack to become larger and larger and eventually rupture.
3. Check whether the current setting meets the process specification. When the thickness of the product changes, the current setting does not increase correspondingly, the welding current is insufficient, and the welding is poor.
4. Check if the welding wheel pressure is reasonable. If the pressure is not enough, the contact resistance will be too large and the actual current will decrease. Although the welding controller has a constant current control mode, the resistance increases beyond a certain range (typically 15%). When the current compensation limit is exceeded, the current cannot be increased when the resistance is increased, and the set value cannot be reached. In this case, an alert is issued when the system is working properly.
5. In actual operation, if the exact cause of the virtual welding cannot be analyzed at the same time, the head and tail of the steel strip can be cleaned, the welding overlap can be increased, the welding current and the welding wheel pressure can be appropriately increased, and one welding can be performed and welded. Pay close attention to the formation of the weld, and in most cases, you can deal with the problem urgently.