The main type of screen changer

Most of the plastic material contains impurities that can be easily removed by a screen changer mounted on the polymer melt flow path after the extruder. The mesh is the same as the diameter of the extruder barrel.

Usually, a set of layers of different heads constitute a package group. The thinnest mesh can filter the smallest solid particles in the melt stream, and the thicker outer layer of the outer layer prevents the larger particles from entering the inner layer too well.

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 protective plate, embedded in the extruder barrel end of the groove.

In order to replace the blocking mesh, first remove the downstream equipment, with a clean mesh to replace the old network, re-installed on the production line.

Screen changer

The method of replacing the network group does not require downtime and labor. According to its design is divided into two main types: interchangeable and continuous.

The interchangeable screen changer has two identical identical groups. One of which is mounted on the melt flow path. When the net group is dirty, replace it with another set of clean ones. At the same time, the old group to get outside the replacement. Two sets of netting are mounted on the same steel plate, rotating about one axis, or sliding along the guide rails. The former is operated manually by the lever, which slides the screen back and forth from one side to the other. Another way to change the network operation is to use a valve, so that the solution from the same group of reverse flow to the same group.

Continuous screen changer: continuous screen changer will move the new network gradually moved to the melt flow at the same time remove the old network. The speed of change of netting can be adjusted automatically according to the amount of impurities, with a continuous screen changer can eliminate the intermittent operation of the network when the pressure and melt temperature changes.

A set of continuous screen changers are designed according to the rotating skateboard. A plurality of web groups are arranged on the perimeter of the ratchet mechanically driven turntable. Turn the turntable, used the old group to move out of the melt flow, before touching the melt flow, hand a new group.

Also some machines use long bars (usually 120 feet long). In the long bar net into or out of the machine parts, a small amount of plastic cooling, hardening can prevent polymer loss. These machines are pulled out of the filter with an external hydraulic pressure. Another design is used in the nose pressure without the external force to pull out the filter.