Ultrasonic welding fixture mainly plays the role of positioning and bearing. For some products with complex three-dimensional surface shape and high machining accuracy, there are also high requirements for the machining accuracy of ultrasonic welding fixture. When the angle or radian of the ultrasonic welding fixture is inconsistent with the welded product, it is easy to cause the deformation of the product after welding.
Generally, the fixture material is aluminum alloy. After the fixture is processed according to the shape of the product to be welded, it is also necessary to change the natural frequency of the fixture through fine adjustment, so that the welding effect is better when the frequency is used with the ultrasonic welding machine. For ultrasonic welding products easy to crack and break, the ultrasonic welding fixture should adopt soft resin or covering cork and other cushioning design. For products that are not easy to break, the welding quality can be improved by surface treatment of ultrasonic welding fixture.
Adjust and optimize the conditions of ultrasonic welding
The conditions of ultrasonic operation refer to the settings of output power, pressure, welding time, cooling time and delay time of ultrasonic welding machine. The ideal welding effect can be obtained by continuously optimizing the conditions of ultrasonic operation.
When implementing ultrasonic welding, if the pressure is too large and the cylinder drops and buffers too fast, it is easy to flatten the ultrasonic welding line. Although the product seems to have been tightly closed, the welding line has been squeezed and sunk, resulting in the loss of welding effect, forming the forced welding of plastic parts surface to surface rather than the guided welding of triangular points, so the welding illusion is generated.
Optimization of ultrasonic welding line
When the welding line design of the product is unreasonable, the product will slip due to pressure during ultrasonic welding, resulting in product dislocation during ultrasonic welding. Alternatively, there is no problem in the design of the welding line, but such problems may also occur because the machining accuracy of the welding line is insufficient, resulting in inconsistent dimensions. Therefore, in mold processing, at least the welding line is required to be symmetrical and consistent in height. Positioning and ultrasonic welding line are the key to success or failure.
Based on the past experience, it is found that there are some quality problems that are easy to occur: scars or cracks on the product surface, distortion, deformation or self color of the product, damage or extrusion of internal parts of the product, displacement and deformation, product burr, the size of the product after welding cannot be controlled and within the tolerance, product dislocation, and the water and gas sealing performance requirements cannot be met after ultrasonic welding.
Generally speaking, the factors affecting the ultrasonic welding effect are concentrated in the following aspects:
Amorphous polymer thermoplastic is an ideal material for ultrasonic welding.
According to the product characteristics and occasions, ultrasonic welding lines generally adopt four modes: triangular welding line, peripheral welding line, peak valley welding line and step welding line.
