Take you to understand the extruder equipment of PE pipe

Extruder

The extruder is one of the important core equipment of the polyethylene pipe production line. In the processing of polyethylene pipes, the most widely used host is a single-screw extruder.

Single screw extruder is a kind of machine developed in recent decades. For many domestic enterprises, the design of single screw extruder is still based on traditional design theory. Therefore, single screw extruder has the following shortcomings :

The torque is small and the squeeze is small.

High content conflicts with stable extrusion.

Large diameter screw determines high output;

Therefore, the traditional single-screw extruder can only extrude raw materials lower than PE63. Due to the limitation of the extrusion volume, it will be difficult to produce if Φ400, PN0 large diameter and high pressure grade PE pipes are extruded. For the No. 8 PE pipe, the traditional model must be a single-screw main engine with a screw diameter greater than 200MM, which increases the processing difficulty of the equipment. More importantly, the output/power ratio is obviously too low and the energy consumption is too large.

In order to ensure the quality of melt and products and continuously improve production efficiency, high-quality single-screw extruders must meet the following requirements:

High torque ensures high extrusion.

The screw diameter is appropriate and the extrusion capacity is extremely high.

The mixing effect is good, the extrusion volume is high, and the stability is good.

In order to achieve the ideal material temperature, the shearing action is strictly controlled to avoid changes in material properties due to degradation and cross-linking.

Better processing adaptability;

For small machines, when they reach a higher extrusion volume, they can only be achieved by using an extruder with an oblique groove sleeve.

The extruder adopts a special structure feeding bushing. There are multiple inclined grooves on the surface of the inner hole. The number and depth of the grooves affect the output of the extruder. A spiral annular groove cooling system is provided on the groove shell. To control the temperature and separate it from the adjacent high-temperature cylinder area. This structure greatly improves efficiency. Therefore, in this system, what determines the output of the entire extrusion line is not the back pressure of the system, nor the depth of the screw groove of the simple feeding part, but the conveying efficiency.

Lian Plastic Machine put forward the concept of "two-stage" for the first time, the purpose is to better improve the plasticization efficiency of the main screw.

The basic principle of the two-stage screw is to combine the advantages of two different screws. In this two-stage screw structure, the plasticization of the material does not completely depend on the compression ratio, nor does it completely depend on the compression ratio. The magnitude of the shear force is mainly reflected in the mixing of materials and mutual heat exchange.

Therefore, the combination of the special oblique groove feed bushing and the double-stage screw embodies a new concept single screw model. The advantages of this model are as follows:

Break the concept of conventional production capacity and achieve the goal of small screw high production capacity.

Effectively and reasonably control the shear of the material to complete its plasticization.

The processing adaptability of the extruder is enhanced, and one machine is multi-purpose and one rod is multi-purpose. For the dual-stage thread system, the barrel thread material should be improved with the traditional nitrided steel material to improve the toughness and bending strength of the thread and improve the sliding efficiency of the barrel thread. There are two specific materials and processing methods. : One is to use bimetallic materials, and the other is to sinter special alloys with alloy materials.