Plastic extruder is also one of the types of plastic machinery. According to the direction of the flow direction of the head and the angle between the center lines of the screw, the extruder can be divided into a right angle head and an oblique angle head. The head of the shell is generally used bolt which are fixed on the frame in the head, inside the mould comprises a mold core seat and then into the line, the head is fixed to the port with nuts, core seat is also equipped with internal core, and the core and core seat center has holes, its role for the wire. Depending on the type of pressure, the extrusion process can be divided into two types: continuous extrusion and intermittent extrusion. The equipment used in the former is a screw extruder, the latter is a plunger extruder. The screw extruder can be roughly classified into a single screw extruder and a multi screw extruder.
The working mechanism of screw extruder is the pressure and shear stress on screw generated by rotating, can make the materials can be fully plasticized and uniformly mixed by die forming; so sometimes use an extruder can also complete mixing, plasticizing and forming a series of process, so as to carry out continuous production. In addition, the working mechanism of the plunger extruder mainly depends on the pressure of the plunger, and the material which is finished in advance is extruded from the die to form the effect. The material in the material cylinder plunger in the extrusion after the return, wait to add a new round of plastic material and then followed by the next round of operation, the production process is continuous production, and the basic material can not be fully stirred and mixed, the production is still in pre plasticizing, so in actual production usually used in this law is only applicable to the poor liquidity or viscosity is very large plastic molding processing, like the cellulose nitrate plastic plastic products.
The plastic extruder can be classified as a twin-screw extruder, a single screw extruder, a small number of multi screw extruder and a screw extruder.