1. Generation of ultrasonic waves
The ultrasonic sewing machine has an ultrasonic generator inside, which converts the mains electricity (usually 220V, 50Hz AC) into high-frequency AC, and its frequency is generally between 20kHz-100kHz.
This high-frequency AC is transmitted to the transducer, which is a device that can convert electrical energy into mechanical energy. It generates high-frequency mechanical vibration under the action of high-frequency AC, thereby emitting ultrasonic waves.
2. Energy transfer and fabric action
The ultrasonic waves generated by the transducer are amplified by the amplitude of the horn and then transmitted to the welding head (also called ultrasonic horn).
When the welding head contacts the fabric to be sewn, the ultrasonic energy is transmitted to the surface of the fabric. Under the action of ultrasonic waves, violent vibrations and friction occur between the molecules of the fabric fibers.
For thermoplastic fabrics (such as fabrics containing polyester, nylon, etc.), the heat generated by this vibration and friction will rapidly heat up the contact points of the fabric fibers. When the temperature reaches the melting point of the fiber, the fibers will fuse together under pressure.
For non-thermoplastic fabrics, ultrasonic vibrations can cause mechanical interlocking between fibers to firmly connect the fabrics.
3. The auxiliary role of pressure
In the ultrasonic sewing process, it is very important to apply a certain amount of pressure. Usually, the machine applies pressure to the welding head through a mechanical device (such as a cylinder or other pressure application system).
This pressure helps to fit the fabrics tightly together, ensure that the ultrasonic energy can be effectively transmitted between the fabric layers, promote the fusion or interlocking of the fibers, and also help to form a tight and neat sewing effect after the fibers are fused.
