1. Basic structure and principle
Single screw extruder is one of the basic equipment in the plastic processing industry, which is mainly composed of screw, barrel, hopper, transmission device, heating and cooling system and extrusion mold. Its core working principle is through the rotation of the screw, the plastic raw materials are sent from the hopper into the barrel, gradually softened and melted under the shear, friction and heat action of the screw and the barrel, and extruded through the mold under the push of the screw.
Screw: Usually made of high-strength alloy steel, with a specific screw groove design, responsible for the conveying, mixing and plasticizing of materials.
Barrel: Closely fitted with the screw, usually made of heat-resistant, pressure-resistant alloy steel or composite steel tube lined with alloy steel, providing the necessary heating and cooling conditions.
Hopper: Used to store and transport raw materials to the screw entrance.
Transmission device: drive screw rotation, usually including motor, reducer and bearings.
Heating and cooling system: used to adjust the temperature of the barrel and screw to ensure the smooth plasticization and extrusion process of plastic raw materials.
Extrusion mold: According to the product shape and size requirements, the molten plastic extrusion molding.
2. Main use
Single screw extruder is widely used in plastic processing industry, mainly used in the production of various plastic products, such as pipe, film, plate, profile, wire and cable sheath. In addition, it is also suitable for the modification, coloring, filling and strengthening of plastics.
3. Advantages and characteristics
Simple structure: single screw extruder structure is relatively simple, easy to operate and maintain.
Adaptable: able to handle many types of plastic raw materials, including thermoplastics and thermoset plastics.
High production efficiency: By adjusting the screw speed and heating and cooling system, continuous and stable production can be achieved.
Lower cost: Compared with twin-screw extruders, single-screw extruders have lower manufacturing and operating costs.
4. Technical parameters
The technical parameters of single screw extruder mainly include screw diameter, screw lengthed-diameter ratio, screw speed, heating power, cooling mode, production capacity and so on. These parameters are selected and adjusted according to specific production needs and feedstock characteristics.
Screw diameter: usually the range is 20-200mm, affecting the production capacity and extrusion pressure.
Screw length-diameter ratio: generally 10-30, affecting the plasticization and mixing effect of materials.
Screw speed: According to raw material characteristics and production needs, usually in the range of 10-200r/min adjustment.
Heating power: According to the length of the barrel and heating requirements to ensure uniform heating of plastic raw materials.
Cooling method: Air cooling or water cooling is usually used to ensure the appropriate temperature of the screw and barrel.
5. Material conveying method
The material conveying method of the single screw extruder is mainly realized through the rotation of the screw. The screw groove design makes the material form a material film between the screw and the barrel, and move forward under the push of the screw. At the same time, the rotation of the screw also produces shear and friction, so that the material gradually softens, melts and mixes evenly.
6. Heating and cooling system
The heating and cooling system is an important part of the single screw extruder and is used to regulate the temperature of the barrel and screw. The heating system is usually heated by electric heating elements or thermal oil to ensure uniform heating and plasticizing of plastic raw materials. The cooling system is usually air-cooled or water-cooled, and the heat is taken away by the heat sink or cooling water pipe to maintain the appropriate temperature of the screw and barrel.
