Main structure and technology of extruder

2020/10/26 11:37:02

Extruder is composed of motr, reducer,distribution box, barrel, screw (barrel screw is a part), heating and cooling device, electric control device.

The core parts of extruder structure are barrel and screw, others are auxiliary devices, but without these devices, they are fixed and vulnerable parts. The material and the mixed dry powder material are pushed into the material trough of the barrel by setting the feeding machine to a certain speed, and the material is naturally pushed into the barrel screw.

Function of each part of extruder screw

Zone 1 : in the process of electric heating and extrusion of the whole extruder, zone 1 plays a very important role, which is more important than other zones

1) Dry powder material compaction, shear, quantitative forward transport

2) As a process of pre plasticizing, if the pre plasticization in zone 1 is not achieved, the plasticization degree of the whole machine will not reach. In the whole extruder (excluding the mold), the temperature in zone 1 is the highest, which is the highest point of temperature. If the first zone is not pre plasticized.

The following conditions will occur:

1.Discharging from exhaust hole of main engine

2.The current increases significantly

3.The product is very brittle.

Zone 2 : in this zone, the dry powder transferred from zone 1 is pressed into blocks through the pre plasticization of zone 1. With the rotation of the screw, the compacted block material is transported forward to zone 2. In this zone, the structure of the spiral bell changes, the spiral bell becomes 4 ~ 5mm thick, and 9 ~ 11 circles of helix are produced, and both ends are disconnected, so the second zone completely meets the standard The plasticization degree is more than 90%.

Zone 3 : the function of this zone is to fully plasticize the materials that are not fully plasticized in zone 2, and ensure that the plasticization reaches 100% in zone 3. Therefore, the third zone of the extruder is also more important. The temperature of the third zone should be 5 ~ 6 ℃ lower than that of the second zone, and the maximum temperature should not exceed 8 ℃. Because the barrel screw material belongs to alloy steel, the rigid material has thermal conductivity, and the temperature step difference is too large to play a role.

Zone 4: this zone does not undertake any plasticizing task. If the material plasticization is quite good, it can be seen that the screw floats on the center of the extruder barrel and rotates. Therefore, the task of the fourth zone of extruder is to transport the plasticized melt forward quantitatively. If this zone undertakes the plasticizing ability, it will do great harm to the extruder.