There Are Higher Requirements for The Production Efficiency And Product Quality of Twin-screw Extruders. Where Can We Start To Optimize Them?

As the manufacturing and processing technology of twin-screw extruders becomes better and better, it not only has to perform tasks such as feeding and plasticizing, but also has some requirements such as dehydration and drying. In order to better meet the different needs of users, the twin-screw extruder must continuously improve its working efficiency, and also find ways to improve the quality of the products produced. So, what should we do?

1. How to improve the working efficiency of twin screw extruder:

Improving working efficiency is one of the key goals of the development and design of the new co-rotating twin-screw extruder. It can also be achieved by increasing the screw speed, improving the plasticization and mixing level, etc. At the same screw speed, increasing the depth of the screw groove can greatly increase the conveying capacity. Correspondingly, the plasticization and mixing level of the screw must also increase, which requires the screw to be able to withstand higher torque.

At high screw speeds, the residence time of the material in the extruder is reduced, which may result in insufficient plasticization, melting and mixing of the material.

Therefore, the screw length must be appropriately increased, which will inevitably result in the twin-screw extruder actually carrying an increase in torque and power.

Increasing the free volume of the screw channel is also a crucial factor. In the feeding section and the devolatilization section, it is very necessary for the screw element to have a large free volume. For bulky materials, expanding the free volume of the feeding section and the filling degree of the material in the screw channel can greatly improve the processing capacity of the extruder.

To increase the torque and speed, the reduction distribution box needs to be carefully designed. To significantly improve the torque index of the equipment, it is necessary to put forward higher requirements for the design and production level of the transmission box.

The higher the torque, the higher the design, manufacturing accuracy, material strength and heat treatment of the gears, output shafts, bearings and other parts in the transmission box must be. At the same time, the design and manufacturing accuracy of the screw's mandrel, threaded elements and kneading discs must also be higher.

Because the free volume of the threaded element needs to be expanded, the center distance between the two screws will be reduced while the outer diameter of the screw remains unchanged, which will inevitably make the problem of insufficient installation space for the matching gear and thrust bearing more prominent.

2. How to improve product quality of twin screw extruder:

To obtain high product quality, the design of the core component of the extruder - the plasticizing system - is of great importance.

The plasticizing system mainly includes a screw and a barrel. In order to meet various types of production and processing requirements, the screw and barrel are generally designed as a building block combination structure. According to the function of each section, the screw can be divided into a feeding section, a plasticizing section, a mixing section, a venting section and an extrusion section. These sections have different functions in the extrusion process, and their structures are not the same. The corresponding screw element geometric parameters are also different. Therefore, how to determine the geometric parameters of the screw element becomes the key to the design of the plasticizing system.

For co-rotating twin screws, there is a certain correlation between the median diameter ratio (i.e. the ratio of the center distance between the two screws to the screw radius), the number of thread heads and the thread top angle. The design scheme cannot be arbitrarily adopted, otherwise there will be interference between the two screws.

To deal with this problem, the author obtained the theoretical end face curve of the screw based on the motion trajectory of the two screws, and used the three-dimensional solid modeling function of large-scale computer-aided design (CAD) software to compile a twin-screw geometric modeling program, realized the three-dimensional solid graphic display of the twin-screw, obtained the geometric parameters of various types and specifications of self-cleaning threaded elements, and tested the meshing of the two screws.

In addition, the project practice is integrated, and with the help of computers, the three-dimensional solid modeling of twin-screws with gaps is completed. This can be used to check whether the gaps between the two screws are uniform, so that there are no dead angles for materials during the movement of the screws. This ensures that the screws have strong self-cleaning capabilities and can effectively prevent materials from staying in the machine for too long and degrading. This undoubtedly provides a good production and processing means for the production of high-end, high-quality plastic products.

NANJING HAISI is professional manufacturer of plastic extruder. we supply Twin Screw Extruder, Single Screw Extruder, Plastic Recycling Extruder, Two Stage Extruder, Lab Scale Extruder, Mixing and Feeding Machine, Cooling and Pelletizing Machine, Crushing Machine and so on.