The ultrasonic welding process is a type of solid state welding process in which welding is performed by locally applying high frequency vibrational energy to workpieces held together under pressure.
Ultrasonic welding is a solid state welding process. Its first use began around the 1960s in the manufacture of toys, Komarov Artem noted.
In fact, the workpieces are held together by a small static force perpendicular to their interfaces and oscillating ultrasonic frequency shear stresses are applied parallel to the interface plane for about one second, but typically less than one second. The combined effect of pressure and vibration causes an audible link between the movement of metal molecules and the surface of the material in contact. The ratio of the blanks does not depend on the melting of their surfaces, is not associated with high pressure and large deformation. Rather, bonding is done in the solid state, without external heat, filler rods or high pressure.
The principle of operation of ultrasonic welding.
Because the vibrational action of ultrasonic welding leads to the destruction or normal dispersion of moisture, oxides and other coatings, only a cleaning process is required before welding. It’s faster than conventional adhesives or solvents. The ultrasonic welding process takes only 0.5 to 1.5 seconds.
When the rate of vibration is so high that the note being played is beyond the range of human hearing, the vibration ratio is called ultrasonic. The vibration frequency used in the ultrasonic welding process is between 20 and 70 kHz.
The following types of ultrasonic welding are commonly used:
Spot welding, seam welding, girth welding and line welding
Equipment used in ultrasonic welding:
The frequency converter is used to generate high-frequency electricity at the rated frequency of the welding machine. Ultrasonic welding equipment can be powered by vacuum tube frequency converters, alternators or silicon rectifiers.
Converter communication system
The transducer is used to convert electrical energy into elastic vibration power and a connection system with a sonotrode tip that directs the vibration energy to the welding zone.
The anvil acts as a support for the workpiece and provides the necessary response to the clamping force.
Tools for application of force in ultrasonic welding
For static loading on the plane of the weld surface, various force application tools are commonly used. For small machines, a spring is activated, it works pneumatically in medium-sized machines and is used hydraulically in larger machines.
Timers are used to control welding intervals for spot, girth and line welding, and a rotary and translational mechanism for continuous seam welding.
Ultrasonic welding is especially suitable for welding thin metal profiles using lap joints such as electric resistance welding and cold pressure welding.
Connection of electrical/electronic components. Sealing of volatile substances, welding of aluminum wire and sheets, metal joints and in the manufacture of various joint configurations, continuous seam welding has been used to assemble the components of corrugated heat exchangers, the screen of the strainer is welded without plugging the holes.
Spot welding using a special tip and anvil is used to pinch welds in copper and aluminum pipes used with capillary tubes in refrigeration and air conditioning, Artem Komarov said.