The definition of parallel co-rotating twin screw extruder
A parallel co-rotating twin-screw extruder is a commonly used machine for the production of a wide array of plastic products, including pipes, plates, films, and injection-molded items. This type of extruder features two screws that rotate in parallel, working together to extrude heated plastic raw materials and shape them into the desired forms. The resulting products are then prepared for further processing.
Parallel co-rotating twin-screw extruders offer several significant advantages for material processing. They ensure efficient mixing, possess self-cleaning capabilities, and offer flexibility through modular configurations. With their high torque capacity, these extruders excel in various industries, making them a versatile choice for achieving consistent quality and performance across a wide range of applications.
Structural features of parallel co-rotating twin screw extruder
The parallel co-rotating twin-screw extruder comprises five key components: the extrusion system, feeding system, transmission system, heating and cooling system, and control system.
- Extrusion system: This component consists of the barrel, screws, and die connector, which includes a porous plate.
- Feeding system: The feeding system includes the hopper, feeder, and feeder transmission mechanism
- Transmission system: This system comprises the motor, reduction gearbox, and thrust bearing.
- Heating and cooling system: Inside the barrel, there are channels for both heating and liquid cooling.
- Control system: The control system is responsible for automating the operation of the entire extrusion unit.
While each part serves functions similar to those in a single screw extruder, it’s worth noting that the structure of parallel co-rotating twin-screw extruder is much more complex than single screw extruder.
Building-block designed screw and barrel
The co-rotating twin-screw extruder stands out due to its distinctive “building block” design, where both the screw and barrel are composed of modular components. The screw assembly encompasses various elements like threaded sections, kneading blocks, toothed mixing discs, and baffle rings, all mounted on a central mandrel. Similarly, the barrel is divided into different sections, including fully enclosed segments, those with exhaust ports, and those with feeding ports.
Customizing these screw and barrel elements to match specific materials, formulations, and performance criteria enables efficient mixing processes. Precisely arranging different types and quantities of these elements in a predetermined sequence is crucial for achieving optimal outcomes. Furthermore, altering the order of screw and barrel elements empowers the machine to effectively process a wide range of materials and formulations, enhancing its versatility and multifunctionality.
Moreover, the modular design offers the benefit of cost-effective maintenance. When certain screw or barrel components wear out, they can be individually replaced, eliminating the need to replace the entire unit and resulting in substantial savings on maintenance expenses.
Benefits brought by structural features
- The primary machine features high-speed co-rotating meshing twin screws capable of facilitating robust material transfer and exchange, intricate blending, precise shearing, and thorough kneading across a range of threads and mixing elements. These functions can be finely tuned and controlled by modifying the screw configuration and adjusting operational conditions to align with the specific demands of various processes.
- New deceleration distribution transmission system, high torque design, high-precision gear processing, imported parts for main bearings, reasonable oil-immersed lubrication combined with forced lubrication device for key parts and interlocking protection device to ensure reliable and smooth operation of the main engine.
- Leverage the confined space efficiently by engineering a cutting-edge involute spline structure mandrel. This design ensures the utmost load-bearing capacity and enables high-torque transmission to be achieved.
Working principle of parallel co-rotating twin screw extruder
The working principle of a parallel co-rotating twin screw extruder is characterized by its unique traits, which set it apart in material processing.
When the screws of a parallel co-rotating twin screw extruder rotate in the same direction, one screw’s teeth extend into the groove of the other screw like a wedge. This arrangement prevents the material from entering the adjacent groove but instead compels it to flow from one screw’s saw groove into the groove of the other screw. As a result, the material undergoes repeated forced circulation between the two screws, experiencing thorough shearing and mixing. When the screws rotate in opposite directions, the material must traverse through the teeth, akin to passing through a mixing gap between two wheels, enhancing the shearing effect.
While the twin-screw extruder process shares similarities with single-screw extrusion, it follows a distinct working principle. On one hand, the twin-screw extruder employs forward conveying to push material forcefully. On the other hand, it generates substantial shearing forces at the intermeshing point of the two screws, significantly intensifying material mixing and plasticization effects.
Moreover, it should be noted that the efficient operation of a co-rotating parallel twin-screw extruder hinges on three fundamental factors.
First, the feed rate, a pivotal parameter, influences both the overall machine’s performance saturation and material formulation. Second, stability within the feeding system, particularly with regard to consistent rotational speed, is essential for ensuring the extruder’s normal functioning and product quality. Finally, the adaptability of the feeding system to the diverse array of materials processed by the parallel co-rotating twin screw extruder, ranging from granules and powders to mixed materials with various additives, poses a significant challenge and remains a key area for future development and improvement. After all, it is very difficult for the same feeding system to stably feed each material.
In essence, the parallel co-rotating twin screw extruder’s unique traits make it a powerful and versatile tool for precise material processing, offering exceptional mixing, melting, pressure control, and product shaping capabilities across a wide spectrum of applications.
Main application areas
Parallel co-rotating twin-screw extruders find widespread application across various industries due to their versatility and efficient material processing capabilities. Some of the main applications include:
- Plastics and Polymers: These extruders are instrumental in compounding and processing materials like Filler Masterbatch, Flame Retardant Masterbatch, Color Masterbatch, and Biodegradable Plastics. They enable precise control over formulations and produce materials used in plastic films, engineering plastics, and more.
- Recycling and Sustainability: Parallel co-rotating twin-screw extruders play a vital role in PET Recycling Granulation, turning recycled PET into reusable materials. They are also employed in producing PLA sheets, contributing to the development of biodegradable plastics.
- Materials Development: These extruders are crucial in Reactive Extrusion, allowing the modification of materials like TPU and Thermoplastic Elastomers for specialized applications. They are also used for Elastomer Granulation and Engineering Plastic Granulation, producing tailored materials for various industries.
In conclusion, the parallel co-rotating twin-screw extruder stands as a remarkable and versatile piece of machinery that has revolutionized material processing across industries. Its synchronized twin screws, working in tandem, enable efficient mixing, compounding, and shaping of various materials, from plastics and polymers to biodegradable options and recycled substances.
With applications ranging from food production to pharmaceuticals and beyond, this extruder has become an indispensable tool for enhancing product quality, sustainability, and innovation. Its adaptability, precise control, and ability to process an array of materials make it a cornerstone of modern manufacturing and materials science, driving progress and sustainability in diverse fields.