Extrusion molding is one of the important molding methods for plastic molding. Most thermoplastics can be extruded to process.

Extrusion has the following characteristics: the production process is continuous, and its products are continuous; high production efficiency; wide range of applications, can produce pipe, bar, profiles, sheet, film, monofilament, wire and cable, and hollow Products, etc .; less investment, quick results.

Extrusion is carried out on an extruder, which is an important breed in plastic molding machines.

The extrusion process is roughly like this: the plastic heating, let it was viscous state, in the case of pressure, so that it has a certain shape of the die, a cross-section with a similar shape of the continuum, and then by cooling stereotypes , To get the required products.

First, the composition of the extruder:

An extruder is generally composed of the following components:

⒈ extrusion system: mainly composed of barrel and screw. Plastic is extruded through the extrusion system into a uniform melt, and in the process of forming the pressure, the screw is continuously pressed, quantified, and the temperature is extruded.

⒉ transmission system: its role is to provide the required torque and speed screw.

⒊ heating and cooling system: the role is through the barrel or screw heating and cooling to ensure that the molding process in the process required to complete the temperature range.

Usually the above three parts of the composition of the host.

⒋ head: the main part of the product molding, molten plastic through the nose to obtain a certain geometric section and size.

⒌ stereotypes device: the role is to come out from the nose with a certain shape of the plastic stabilized, and its finishing, so as to get more accurate cross-sectional shape, size and bright surface; usually with cooling and pressure method Achieve their goals.

⒍ cooling device: from the stereotypes of the plastic out here to get full cooling, to obtain the final shape and size.

⒎ traction device: uniform traction products, and the cross-sectional size of the product control, so that the extrusion process is stable.

⒏ cutting device: the continuous extrusion of the products cut into a certain length, width.

⒐ coiling device: the soft products (such as film, hose, monofilament, etc.) winding up.

Generally will be part of the machine after the machine called auxiliary; according to the different products, auxiliary equipment can be composed of different parts of the above, more or less.

⒑ Extruder control system: composed of a variety of electrical appliances, instruments, actuators, can control the extruder host, auxiliary machine drag the click, drive the pump, cylinder, cylinder and other actuators in accordance with the required Power, speed and trajectory operation, as well as the detection and control of the main and auxiliary machine temperature, pressure, flow, and ultimately to the entire extrusion unit of the automatic control of the product control products.

Usually the above 1 to 10 parts of the device is called the extrusion unit.

Second, the extruder classification: With the increase in the use of extruder appeared all kinds of extruder, there are different classification methods.

⒈ by the number of screws divided into: single screw extruder, twin screw extruder, multi-screw extruder;

⒉ according to whether the exhaust can be divided into: exhaust type extruder, non-exhaust type extruder;

⒊ by the presence of the screw is divided into: screw extruder, no screw extruder;

⒋ according to the screw space is divided into: horizontal extruder, vertical extruder.