There are two types of spot welding of ultrasonic welding machine: surface spot welding and single-sided spot welding. The welding characteristics of the two categories are also different. For example, in double-sided spot welding, the electrodes are fed from both sides of the workpiece to the welding place. The conductive plate of the welding area is used as the lower electrode, which can eliminate or reduce the indentation of the workpiece below.

  

      The single-sided spot welding technique of the ultrasonic welding machine is mainly that the electrode is fed from the same side of the workpiece to the welding place. The typical single-sided spot welding is single-sided single-point spot welding. The electrode that does not form a welding spot uses a large diameter and a large contact surface. To reduce the current density. Single-sided double-point spot welding without shunt, at this time all welding current flows through the welding zone. In the figure, C has a shunt single-sided double-point spot welding, and the current flowing through the upper workpiece does not pass through the welding area, forming a wind current. In order to provide a low-resistance path for the welding current, a copper backing plate is placed under the workpiece. In the figure d is when the distance l between the two solder joints is very large, for example, when welding the skeleton member and the composite board, in order to avoid the warping of the composite board caused by inappropriate heating and reduce the resistance between the two electrodes, a special The copper bridge A is pressed against the workpiece at the same time as the electrode.

      Especially in mass production, the two techniques of ultrasonic welding machine are used very much, especially single-sided multi-point spot welding is widely used. At this time, a transformer can be used to supply power and each pair of electrodes press the workpiece in turn, or a separate transformer can be used to supply power to each pair of electrodes, and all electrodes can press the workpiece at the same time (Figure 11-7b). The latter type It has many advantages and is widely used. Its advantages are: each transformer can be placed closest to the connected electrode, therefore. Its power and size can be significantly reduced; the process parameters of each solder joint can be adjusted individually; all solder joints can be soldered at the same time, with high productivity; all electrodes simultaneously press the workpiece to reduce deformation; multiple transformers are energized at the same time to ensure three-phase Load balance, and achieve the best welding effect of ultrasonic welding machine.