The extruder screw is a key component of the extruder, and its performance determines the performance of the extruder. Therefore, optimizing the design of the extruder screw is a very important task. Generally speaking, the more objective functions, design variables, and constraints there are in the optimization design mathematical model, the more complex and difficult the design and optimization processes are. People are committed to seeking optimization design methods for important geometric parameters of the screw, such as screw angle, groove depth, clearance between the screw and barrel, and length-to-diameter ratio, under predefined optimization objectives. Next, let's take a look at the methods for optimizing the design of extruder screws.
The commonly used methods for optimizing the design of extruder screws are: the mathematical extremum method (analytical method) under simplified conditions, the graphical method, and the orthogonal design method based on experiments, statistical analysis, and CAD.
1. Analysis method.
This method has been used earlier. Usually, the optimization of design variables is carried out under a single optimization objective (such as output or power consumption). The optimization method is the method of finding extremum in advanced mathematics; for example, it can be seen from formula (1). Without considering pressure changes and screw friction factors, the maximum value can be achieved. Therefore, formula (1) can be written as.
2. Diagram method.
When the design variables to be considered are not single variables, or when the design variables are expressed in the form of a certain functional relationship, the optimal range of parameters can be directly displayed graphically. For example, from equation (1), it can be seen that when other parameters remain unchanged, the production capacity is proportional to Tg capacity * Tgθb / (Tg ratio Tgθb). Taking f. = fB, D = 50 mm, H = 10 mm, the relationship curve of Tg * Tgθb / (Tg T Tgθb) versus θ is plotted. Therefore, the design of most bolts currently is such that when θb is 17.66, the pitch equals the diameter.
3. Orthogonal design method.
As mentioned earlier, there are many variables in screw design, and there may be some relationships between them, which can sometimes be very complex. In such cases, using experimental methods to determine the optimal range of design variables is often more effective. However, if conventional experimental methods are used, hundreds or even thousands of experiments would be required. Time-consuming orthogonal design is a scientific method that seeks the best experimental results with the minimum number of trials according to certain rules (orthogonal tables). Based on the analysis of influencing factors, and according to the combination principles in the orthogonal table, the required levels of each factor are selected, and the experimental results are analyzed orthogonally to determine the optimal design parameters. To better analyze the experimental program, the main factors can also be evaluated.
The commonly used methods for optimizing the design of extruder screws are: the mathematical extremum method (analytical method) under simplified conditions, the graphical method, and the orthogonal design method based on experiments, statistical analysis, and CAD.
1. Analysis method.
This method has been used earlier. Usually, the optimization of design variables is carried out under a single optimization objective (such as output or power consumption). The optimization method is the method of finding extremum in advanced mathematics; for example, it can be seen from formula (1). Without considering pressure changes and screw friction factors, the maximum value can be achieved. Therefore, formula (1) can be written as.
2. Diagram method.
When the design variables to be considered are not single variables, or when the design variables are expressed in the form of a certain functional relationship, the optimal range of parameters can be directly displayed graphically. For example, from equation (1), it can be seen that when other parameters remain unchanged, the production capacity is proportional to Tg capacity * Tgθb / (Tg ratio Tgθb). Taking f. = fB, D = 50 mm, H = 10 mm, the relationship curve of Tg * Tgθb / (Tg T Tgθb) versus θ is plotted. Therefore, the design of most bolts currently is such that when θb is 17.66, the pitch equals the diameter.
3. Orthogonal design method.
As mentioned earlier, there are many variables in screw design, and there may be some relationships between them, which can sometimes be very complex. In such cases, using experimental methods to determine the optimal range of design variables is often more effective. However, if conventional experimental methods are used, hundreds or even thousands of experiments would be required. Time-consuming orthogonal design is a scientific method that seeks the best experimental results with the minimum number of trials according to certain rules (orthogonal tables). Based on the analysis of influencing factors, and according to the combination principles in the orthogonal table, the required levels of each factor are selected, and the experimental results are analyzed orthogonally to determine the optimal design parameters. To better analyze the experimental program, the main factors can also be evaluated.