Design And Optimization Of Control Process For Polymer Ultrasonic Precision Welding

As a fast and efficient welding technology,ultrasonic welding technology has many advantages such as no heat treatment,short bonding time,high efficiency and local heating.With the widespread application of ultrasonic welding technology in the field of polymer microdevice manufacturing,how to improve the controllability of the polymer microdevice welding process and the accuracy of the welding behavior have become the most important.Based on the ultrasonic vibration detection function,this paper combines the mechanical properties of amorphous polymers and the characteristics of vibration transmission at the polymer welding interface,and develops the relationship between the characteristics of vibration transmission and polymer physical state changes during ultrasonic precision welding of polymers Research,further optimized the precise ultrasonic polymer control process,and improved welding accuracy.In order to better study the relationship between vibration transmission characteristics and physical state changes,the influencing factors that affect the vibration transmission characteristics of the welding process were investigated through experiments.The test selected a polymethylmethacrylate(PMMA)micro-connected tube and The welding of substrates was studied,and combined tests were performed using substrates,no substrates,silicone pads,and no silicone pads during the welding process.After experimental demonstration and wavelet packet decomposition and reconstruction analysis of the extracted vibration information,it is proved that the partial welding of the connecting pipe is expected and the use of silicone gaskets during the welding process can effectively extract the vibration transmission characteristics,and at the same time remove redundant interference,and get more For obvious vibration characteristics.Based on the extraction and analysis of the characteristic waveforms of vibration transmission,the control flow of ultrasonic polymer precision welding was optimized,and a four-stage control flow was designed based on the change of the positive and negative amplitude relative amplitude in a short period of time.Based on the changes,the welding process is divided into three main stages and a completion stage.In the first stage,the peak of the first vibration characteristic waveform is the feature point I,the second stage is the appearance of the valley as the feature point II,and the third stage is the second wave peak as the feature point III.The final completion stage does not change in amplitude and stops welding.This control process effectively intercepts the polymer physical characteristics at different stages.By analyzing the vibration characteristic waveforms of each stage and the welding effect of the welding interface,the selective control of the fusion degree of theinterface during the ultrasonic polymer precision welding is achieved,which improves the welding Precision and welding quality.Under the action of ultrasound,the temperature of the polymer increases.When the welding boundary is converted to a viscous flow state,the ultrasonic cavitation effect is prone to occur,which affects the welding quality.In order to optimize the welding quality and further improve the welding precision,non-constant polymer ultrasonic precision welding control process is designed based on the mechanical properties of the thermoplastic polymer under the action of ultrasonic state transition.The test was carried out with the change rate of dynamic pressure during the welding process as the control parameter.The dynamic force curve and the effect of the fusion interface extracted from the test proved that changing the amplitude can improve the welding quality.Changing the amplitude of the applied ultrasonic wave during the welding process can reduce the load on the welding interface in the viscous state,effectively reducing the influence of the ultrasonic cavitation effect on the welding effect,and improving the welding quality.