Important Parameters Setting of Double Screw Extruder During Operation

In pulverizing equipment, double screw extruder is a key equipment and the model with the most reserves in the extruder. Although it has been increasingly improved in design and manufacturing and can process various types of powders with satisfactory results.

Setting of melting temperature of double screw extruder

In order to blend, the ingredients must be heated, especially the meltable components must be completely melted as soon as possible and maintained at a certain temperature (i.e. the set temperature) to become the envelopes of various immiscible components in the composition and be mixed together. Therefore, the set temperature has two purposes. First, to melt the meltable components as soon as possible, the shorter the melting time, the smaller the length proportion of the position occupied in the barrel, the longer the mixing time, and the better the mixing effect. Second, to limit the startup of the cooling machine when the temperature rises to a certain value, preventing solidification of materials.

In the melting zone, the material temperature is low and heat absorption is mainly dominant, so the set temperature should be high, but it is not satisfactory to set it low in the early use of the manual because the screw speed and output are low there.

As the material advances slowly in the barrel, there is plenty of time to heat up. It is good to increase the set temperature, but the temperature of the feeding section may rise too high, and the conveying capacity of the screw weakened or lost due to the increased melting material in this section, which causes people to "be cautious".

Therefore, with the accumulation of people's experience and the improvement of the theoretical level, especially the continuous improvement of the screw speed of double screw extruder (the 60 screws have reached a thousand revolutions), and the strengthening of the research on the temperature field of the barrel, new understanding has emerged.

As long as the cooling effect of the feed section is guaranteed, or lower-temperature cooling water can be used, or good insulation measures are taken between the melting section, or there is an internal cooling facility, etc., even if the set temperature of this section is higher than the solidification point, it is not a problem.

In short, the set temperature of the feeding section should be high, and the specific value should be close to the solidification temperature and proportional to the screw speed or the material's advancing speed in the barrel.

Setting of temperature in other working zones of double screw extruder

The principle of setting the temperature in the zones before the melting zone is to gradually decrease. The lower the screw speed, the more it decreases. High-speed machine models for non-gloss powder processing should be set to decrease less or even not.

Adjustment of working speed of double screw extruder

After the main motor starts smoothly, it should be operated at the rated speed as much as possible, and the main current should be maintained at (90-95)% of its rated current value.

The correct startup procedure is to first adjust the melting zone temperature higher than the softening point of the meltable material by (10-20)℃ as a startup setting. After the steady acceleration reaches (25-30) Hz, the feeding machine is turned on and slowly accelerated. At the same time, the melting zone temperature setting value is adjusted back, and when the main current approaches the rated value, the feeding machine stops accelerating; then the main motor is accelerated to 35 Hz and the feeding machine is adjusted again.

Repeat the above operation, each time the main motor increases its speed by about 5 Hz until the rated speed (50 or 60 Hz). The whole process should not be too fast. Sometimes the main current may slightly exceed the rated value when adjusting the feeding machine, which is not a problem. It will immediately come down when the main motor speeds up, but the feeding amount must be reduced at the rated speed.