Introduction to the screen changer knowledge

In the plastic extrusion process, whether it is extrusion blown film or extrusion profiles, sheet, film, granulation and other products, due to the possible impurities in the plastic, other foreign body, and unplasticized fine plastic particles, if Do not use the screen changer for filtering, often resulting in defective or even extruded products interrupted, resulting in a lot of waste, so that production costs increase.

The rewinding system is an important part of the extrusion process, especially for plastic recycling and filler production.

The rewinding system is usually composed of a screen changer and a power system, wherein the screen changer is composed of a body, a sealing assembly, a perforated plate, a filter and a switching device.

The material selection of the changer components is very important. Ordinary carbon steel can not meet the requirements of high hardness, wear resistance, short service life and easy leakage. General components should be made of alloy steel, especially the sealing components and switching devices to use high-quality alloy steel by a special heat treatment process to achieve high hardness, high wear resistance, so as to ensure that the screen changer in the high temperature and pressure is not deformed, thus To ensure the accuracy of the screen changer, long-term use does not leak material.

The filter is a woven wire mesh or stainless steel mesh. Usually by a few layers of different mesh network constitute a group.

The outer layer of the thick mesh is stronger, can prevent the larger particles prematurely into the inner layer of fine network.

The thinnest mesh in the inner layer filters the smallest solid particles in the melt stream.

The choice of filter according to different products, raw materials to choose the degree of cleanliness.

General granulation, pipe production using 100 mesh below the filter.

Sheet, sheet production can choose 100-200 mesh filter

Film and transparency requirements of the higher products selected more than 200 mesh filter.

In order to resist the force generated by the melt flow, the filter group lining a dense hole of the circular steel plate, called the porous plate or honeycomb board, embedded in the screen changer of the screen or mesh, or directly installed in the extruder Barrel.

Power system is generally divided into hydraulic drive, motor direct drive.

Hydraulic drive is generally through the hydraulic oil drive cylinder to drive the screen changer skateboard or mesh for the network work

Direct drive motor is driven by the screw drive up and down the skateboard for the network.

Screen changer according to the actual production needs, more types, the current market use of the network converter generally have the following types:

Continuous tape changer, rotary screen changer, plate changer, column changer.

Which take the tape changer because the material waste, easy to leak material, etc. are gradually eliminated

Rotary screen changer because the domestic technology is not mature, the manufacturing cost is bigger, the domestic use of the customer less.

Plate changer and column changer due to the original extrusion equipment is not too much change, can be directly installed in any type of plastic extruder head, the technology is mature, simple to manufacture, the use of low cost, Easy to install and be widely used by domestic customers. So loved by domestic customers.