Optimization on ultrasonic plastic welding systems based on two-dimensional phononic crystal

Large-sized tools are needed for plastic welding of large objects. However, the displacement distribution at the radiation surface of the tools is not uniform due to the strong lateral vibration. In this paper, two-dimensional (2D) phononic crystal (PnC) is introduced by processing periodically arranged grooves in large-sized tools. This method is different from the traditional experience-based grooving method. The lateral vibration is suppressed due to the characteristic of PnC. In this paper, six kinds of ultrasonic plastic welding systems based on 2D PnC with different groove width and height are designed. The vibration characteristics of ultrasonic plastic welding systems were simulated and experimented. The band gaps of large-sized tools are analyzed. The results show that the lateral vibration is suppressed when the operating frequency of the ultrasonic plastic welding system is within the band gap of the large tool. The displacement distribution at the radiation surface of the tools is more uniform. A theoretical support is provided for the design of large-sized ultrasonic plastic welding systems.