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Plastic Single Screw Extruder The Calculation Method Of

Design and development direction of single screw extruder

Plastic Single Screw Extruder In single screw plastic extruder, the correct screw size is a very important factor influencing the quality and cost of extrusion products. It is feasible to make some necessary assumptions and simplification in the design process, and most equipment manufacturers have some technical know-how in designing the extrusion machines with certain use, and they can develop further by researching the new design methods.

Plastic Single Screw Extruder The goal of the screw design is to define the proper geometric shape of the screw, the rotational speed of the screw required for a given yield, and the required heating capacity. The specific design is generally the combination of extruder, mould head and material. Even if we do not consider high yields, we should also consider the design process of the lowest wastage, high-quality mixing uniformity and low energy consumption.

Plastic Single Screw Extruder Mixing components are used to make the material mixed evenly, broken solid beds, melting residual particles and guaranteed to be completely mixed. According to specific requirements, the screw design is to choose suitable for crushing materials or the imposition of shear stress screw. It is difficult to define a uniform standard for mixing quality. In general, the comparison of the inlet and outlet temperature distributions of the mixing segments can be used as a measure of the thermal mixing effect. 

Plastic Single Screw Extruder In addition to the shear force or deformation of each beam of the surface area and mixing section, we can obtain the method of measuring the mechanical dispersion or crushing efficiency of the mixing element. Various materials and machining processes lead us to design a variety of possible geometric shapes of different screw rods. As a result of the product diversity to the equipment installation requirements, more and more use of a variety of raw materials to be evenly mixed and high-quality machining screw, however, so for a specific purpose of the design of the screw did not play its potential high yield and high quality.

1, Plastic Single Screw Extruder single screw plastic extruder calculation method

Plastic Single Screw Extruder In the design of extruder screw, there are many methods, design parameters can be determined by approximate equations, the geometric shape of simple screw in the neglect of many influential factors is possible, but this obtained design parameters are not suitable to estimate the modern screw extrusion process.

Plastic Single Screw Extruder Another method is model theory, which can be used in the batch production of extruder in the experiment, but it has considerable limitations and requires complex laboratory scale experiments. More importantly, the size ratios of laboratory models and production machines are not necessarily large. We can increase the number of parameters to be considered by simulating methods. Through simulations we can get key data on some important materials.

Plastic Single Screw Extruder Because of the difficulty of modeling material and boundary conditions, it is very complicated to simulate conveying segments, transition segments and homogenization segments with standard finite element program. The various parts of the extruder can be simulated with the standard finite element, and the workload of geometric modeling, boundary conditions and material properties is very large. This means that, because of the cost, the standard finite element can be used in the design of screw rod is limited. A new method is the boundary element method, which simplifies grid partitioning and shortens computation time, and can predict the pressure distributions of flow rate, shear stress, streamline and all geometric simulations. The calculation of boundary element method is carried out under isothermal conditions. A mixture of materials in a mixing segment has been proven to be successful in simulations.

Plastic Single Screw Extruder The correct analysis of the results of the simulation is important because the computational data of the program is only qualitatively correct, but it is not always accurate enough to quantify. In particular, the accuracy of the results depends on the accuracy of the existing material data. Another factor influencing the accuracy of the result is whether the simulation program can consider all relevant factors influencing the simulated screw. 

Plastic Single Screw Extruder The difficulty of simulating and analysing screw rod makes most production companies still use their own approximate calculations, supplemented by experimental attempts and program simulations. In reality, the screw design is still based on the experience of designers, the simulator allows engineers to inspect various geometric shapes and machining parameters in a shorter period of time. This means that, in the creation of the modern extruder industry, they really play an important role. In the future, more sophisticated simulations will be able to draw a large number of and precise parameters. In the development of single-screw extruder, analog processing will continue to play a more important role.