Ultrasonic welding impeller can improve the reliability of pump operation and effectively prevent faults. The diameter of plastic impeller of automobile water pump is generally between 8mm-14mm. Due to the limited injection technology and the particularity of plastic impeller structure, it can not meet the one-time injection molding. The injection molding is usually split in two parts. Assembling the products with ultrasonic welding machine is the core component of automobile water pump The main plastic material is PPS, nylon and a small amount of glass fiber
According to the statistics on the welding site of plastic impeller, if the welding mechanism of injection molded impeller parts is not designed in advance during the injection molding period in the early stage, 80% of the defective products of water pump impeller will exist in the welding process of ultrasonic welding impeller. The main reasons are serious welding slag in the internal flow channel, flash, false welding and even unreliable welding, In order to improve the product qualification rate and better avoid these problems, it is necessary to improve the structural design of injection mold before welding from two points:
The ultrasonic welding line does not need a full circle, but can carry out intermittent lattice structure, which ensures that there is enough plastic to ensure the strength of the impeller after welding, and there will be no excess plastic overflow to cause welding slag
The injection molded parts of the plastic impeller of the feed pump must be designed and assembled with positioning columns. If there is no positioning column in the early stage, the energy loss caused by the high-speed ultrasonic vibration will directly affect the poor welding and the welding is not firm
Another point is that the selection of ultrasonic welding machine is also very important. It is best to choose 20kHz and 3000W ultrasonic welding machine, because it has high power and can adapt to direct impellers of different sizes
