When the ultrasonic welding machine is used for plastic welding work, the temperature of the ultrasonic vibration system should not exceed 85 ℃ at any time. When using ultrasonic vibration systems, including ultrasonic transducers and ultrasonic molds, heat is generated for three main reasons:
One is the heating of the material to be heated by the weldment or the ultrasonic treatment when the plastic is welded, or the ultrasonic mold (tool head), the working heat of the ultrasonic variable rod length, and these heat will be transmitted to the ultrasonic mold.
The second problem is the power loss of the ultrasonic sensor itself. Since the energy conversion efficiency cannot reach 100%, the energy loss must be converted into heat. An increase in temperature causes a change in the sensor parameters and gradually changes the state of the best match. More seriously, the temperature increase will lead to the deterioration of the performance of the piezoelectric ceramics. This in turn causes the sensor to work worse and heat up faster, a vicious cycle. Therefore, the inverter must be provided with good cooling conditions, usually using room temperature air cooling; if necessary, cold air blast cooling can also be used. Under normal circumstances, the temperature rise caused by these two points is also normal. Under normal cooling conditions, there should be no major problems.
In practice, we found that there is a third reason, that is, the user fails to match the sensor and the driving power to the best working condition when using the sensor. The resulting heat is very large, uncontrollable, and the consequences are serious. Heating of any part of the vibration system will affect the working state of the entire system. In severe cases, the ultrasonic sensor, ultrasonic mold or ultrasonic generator will be damaged.