The screw of the injection molding machine is an important part of the plasticization part of the injection molding machine. The quality of the screw barrel is of vital importance for improving the quality and quantity of the molded products of the injection molding machine.
First: improve production efficiency
Improving production efficiency is one of the important goals of the development of the new co-rotating twin-screw extruder. It can be achieved by increasing the screw speed, enhancing the plasticizing and mixing capabilities. Under the same screw speed, increasing the depth bimetallic screw barrel of the screw groove can greatly increase the conveying capacity.
Correspondingly, the plasticizing and mixing capacity of the screw is also required to increase, which requires the screw to withstand greater torque. At a high screw speed, the residence time of the material in the extruder is reduced, which may cause the material to be plasticized, melted, and mixed sufficiently.
For this reason, it is necessary to appropriately increase the length of the screw, which will inevitably lead to an increase in the actual load torque and power of the twin-screw extruder. Increasing the free volume of the screw groove is also an important factor. In the feeding section and devolatilization section, it is very necessary for the screw element to have a large free volume. For bulk materials, increasing the free volume of the feeding section and the filling degree of the material in the screw groove can greatly improve the production of the extruder. ability.
Second: Improve product quality
To obtain high product quality, the design of the plasticizing system, the core component of the extruder, is of great importance.
The plasticizing system mainly includes a screw and a screw barrel. In order to meet a variety of processing requirements, the screw and screw barrel are usually designed as a modular structure. According to the function of each section, the screw can be divided into feeding section, plasticizing section, mixing section, exhaust section and extrusion section. These sections have different functions in the extrusion process, their structures are different, and the corresponding geometric parameters of the screw elements are also different. Therefore, how to determine the geometric parameters of the screw elements becomes the key to the design of the plasticization system. For co-rotating twin screws, there is a certain relationship between the pitch diameter ratio (that is, the ratio between the center distance of the two screws and the screw radius), the number of screw threads, and the screw apex angle. It cannot be designed arbitrarily, otherwise it will happen between the two screws. put one's oar in.
In addition, combined with engineering practice, with the aid of a computer, a three-dimensional solid model of a twin screw with a gap is completed, which can be used to test whether the gap between the two screws is uniform, so that the material has no dead angles in the screw movement, that is, to ensure that the screw has a strong self The cleaning ability can effectively prevent the material from staying in the machine for too long and degrading, which undoubtedly provides a good processing method for the manufacture of high-end and high-quality plastic products.
In addition, optimize the combination of threaded components in the exhaust section, set up pressure building components in front of the exhaust port, and use large-lead threaded components to improve the devolatilization efficiency; in addition, use melt gears between the die and the extruder The pump builds pressure, which reduces the pressure at the end of the metering section of the extruder, shortens the effective filling length of the screw, and increases the effective exhaust length, which can improve the exhaust effect to a certain extent.