The invention provides a device and a method for preventing material backflow in the vacuum section of an extruder. The device includes an extruder barrel, a vacuum cavity assembly, a vacuum pumping assembly and a safety valve. The safety valve consists of a valve sleeve assembly, a valve core assembly and a thermal induction actuator. The thermal induction actuator is designed to trigger phase change and drive the valve core to open the passage when molten materials approach and transfer heat to the actuator inside the vacuum cavity. The simple mechanical structure effectively avoids vacuum backflow and supports timely sound alarm to remind workers of process adjustment and cleaning, improving product quality and production efficiency. The solution requires no optical elements, circuits or sensors, featuring high reliability, low cost, simple modification on existing equipment, stable operation and consistent product quality.

Area Code: CN

Application Number: CN201910768947.X