How to solve the feeding problem in the modified granulation process of extruder?
The essence of the material problem of the exhaust port depends on the material flow Q2 < material flow Q1 of the extruder screw exhaust section. (This is true for both natural and vacuum vents in the same direction) Considering the difference in axial position, temperature and material condition of extruder screw of the two exhaust ports, it is better to separate them. I. Interpretation and analysis of material return from natural exhaust port (phenomenon, reason and measures) 1. Exhaust port emits powder A. The proportion of powder in the feed is too high or the moisture of powder is too high (reduce the proportion of powder or pre-dry); B. Powder is sprayed at the exhaust port and water vapor is enfolded (too much moisture in the powder and too strong kneading area in front, water vapor in the barrel is inverted); C. The axial distance between the side feeder and the natural exhaust port is too close (rearrange the position of the cylinder blocks). 2. The exhaust orifice emits glue A. Shear strength is too strong in the kneading area in front of the natural exhaust port, and it is difficult to push the glue; B. The cylinder temperature in front of the natural exhaust port is set too low. II. Interpretation and analysis of glue return at vacuum exhaust port 1. Host reason A. The resistance of the kneading zone in front of the first vacuum opening is too large (rearrange the extruder screw configuration); B. The vacuum degree of the exhaust chamber is too high (the vacuum degree is reduced to a reasonable value); C. The thread sleeve of measuring section is seriously worn and the displacement is insufficient (replace the thread sleeve meeting the standard); D. The temperature Settings of the front and rear cylinders of the vacuum exhaust port are inverted (reset and adjust the temperature in place); E. The twin-screw measuring section is too short, such as underwater heating of TPU (measuring cylinder is lengthened to two sections). 2. Net changer or nose reason A. The filter net has not been cleaned for a long time (stop and change the net, and insist on regular cleaning); B. Combined mesh resistance is too large (please have experience to adjust the mesh of each layer); C. The water temperature of the hot granule on the die surface (underwater or water ring) process is too low (appropriately raise the water temperature); D. hot particles on the die surface, less die holes (high melting pressure). (Change the mold head). 3. Other reasons Other causes of exhaust port material return. Once it occurs, interpret and analyze the cause and seek action! Such as: A. The extruder screw elements (thread sleeve, kneader block, toothed disc, etc.) in a certain area are suddenly broken;
B. The temperature in an area is suddenly out of control (the electric heating tile or electric heating rod is damaged, or the temperature control solenoid valve fails, or the temperature sensor is damaged, etc.)
C. Glass fiber roving wrapped rod, resulting in plastic melt blockage, etc.
Exhaust type extruder screw whether material, and the extrusion process, the plastic performance and extruder screw and vent design has a direct relationship, so the producers in the use of exhaust type plastic granulation extruder during production and processing, to the processing technology and resin properties and equipment performance to make detailed understanding, can make the exhaust type plastic extruder is normal and stable operation.