What effect does the pressure change have on the effect of ultrasonic welding ?

   In ultrasonic welding, the welding pressure is transmitted to the weldment through the cylinder. Different materials determine the pressure needed in the welding process. Choosing a suitable pressure has a significant impact on the effect of ultrasonic welding. 

    Pressure regulation of ultrasonic welding machine has a great influence on the thickness and orientation of melt zone in ultrasonic welding. With the increase of welding pressure, the thickness of melt layer decreases, and the orientation degree of welded joint increases. Macroscopically, the welding pressure increases, the shear strength along the orientation direction increases, and the bending strength perpendicular to the orientation direction increases. Lower.

Under certain conditions, the faster the descending speed of the welding joint is, the higher the strength of the welded joint is. In the process of ultrasonic welding, high descending speed can obtain high contact pressure, which is beneficial to the close contact of welding interface and the full diffusion of molecules.

After the stop of ultrasonic wave, in order to make the welded specimens close to each other and solidify, so that the two workpieces can be welded together well, it is necessary to maintain a certain pressure in a certain period of time. The required time and pressure are the holding time and the holding pressure.The effect of holding time and pressure on the strength of welded joints is positive, but compared with other process parameters, holding time and pressure have little effect on the strength of welded joints.

    If the welding pressure is too low, the ultrasonic physical vibration can not be transmitted to the welded parts very well, resulting in insufficient friction between the welded surfaces, energy will be lost on the friction of the welded surface, the result is that the effective welding effect can not be formed. If the pressure is too high, the friction force is too large, the friction motion between the welds is weakened, and even the ultrasonic vibration can not be transmitted directly because of the pressure too large. As a result, the area of connection between the welds does not increase but decreases, and the strength of the welding will also decrease.

    Therefore, choose a suitable welding pressure value, so as to make the contact area in a large range, the connection area is large, and the welding strength of the end joint is large.