How the extruder works

Extruder definition introduction

In the plastic extrusion molding equipment, the plastic extruder is usually called the main machine, and its supporting subsequent equipment plastic extrusion molding machine is called the auxiliary machine. After more than 100 years of development, plastic extruders have been derived from the original single screw into a variety of models such as twin screws, multi-screws, and even no screws. Plastic extruder (host) can be matched with pipe, film, holding material, monofilament, flat wire, packing belt, extrusion mesh, plate (sheet) material, profile, granulation, cable coating and other plastic molding auxiliary machines to form a variety of plastic extrusion molding production line to produce a variety of plastic products. Therefore, whether now or in the future, plastic extrusion molding machinery is one of the widely used machines in the plastic processing industry.

The working principle of plastic extruder Screw extruder is one of the most important equipment for plastic molding processing, it through external power transmission and heat transfer of external heating elements for plastic solid transport, compaction, melting, shearing and mixing extrusion molding. Since the birth of screw extruder, after nearly a hundred years of development, it has been developed from ordinary screw extruder to a new type of screw extruder. Although there are many types of new screw extruders, in terms of the extrusion mechanism, it is basically the same. The extrusion process of traditional screw extruder is realized by heating outside the barrel, the friction force between solid materials and the barrel, the screw and the melt shear force. "Friction coefficient" and "friction force", "viscosity" and "shear stress" are the main factors affecting the performance of the traditional screw extruder, because the factors affecting "friction" and "viscosity" are very complex, therefore, the traditional screw extruder extrusion process is an unstable state, difficult to control, especially for some poor thermal stability and high viscosity heat sensitive plastics. Since the 1960s, scholars around the world have carried out a lot of research on the mechanism of screw extrusion, and have also made obvious achievements, but because their research is mostly limited to the traditional plastic extrusion molding mechanism, mechanical structure and energy exchange mode, it has not been able to make a major breakthrough. A series of shortcomings of traditional screw extruders such as large volume, high energy consumption, loud noise, and difficult to improve product quality have not been fundamentally solved.

Plastic extruder features

1. Modularity and specialization

Modular production of plastic extruders can adapt to the special requirements of different users, shorten the research and development cycle of new products, and strive for greater market share; The specialized production can arrange the various system module components of extrusion molding equipment for fixed-point production or even global procurement, which is very beneficial to ensure the quality of the whole period, reduce costs, and accelerate capital turnover.

2. Efficient and multi-functional

The high efficiency of plastic extruder is mainly reflected in high output, low energy consumption and low manufacturing cost. In terms of function, screw plastic extruder has not only been used for extrusion molding and mixing processing of polymer materials, its use has been expanded to food, feed, electrodes, explosives, building materials, packaging, pulp, ceramics and other fields.

3. Large scale and precision

The realization of the large-scale plastic extruder can reduce the production cost, which is more obvious in the large twin-screw plastic granulation unit, film blowing unit, pipe extrusion unit and so on. The major technical equipment required for national key construction services, and the large extruded granulation unit, one of the three key equipment supporting large-scale ethylene projects, has long relied on imports, so it is necessary to speed up the localization process to meet the development needs of the petrochemical industry.

4. Intelligent and networked

Plastic extruders in developed countries have generally adopted modern electronic and computer control technology, and the process parameters of the entire extrusion process such as melt pressure and temperature, the temperature of each section of the fuselage, the main screw and feeding screw speed, the feeding amount, the ratio of various raw materials, the current and voltage of the motor are tested online, and the microcomputer is used for closed-loop control. This is very beneficial to ensure the stability of the process conditions and improve the accuracy of the product.