Its core lies in precisely compounding two or more polymer melts with distinct properties (such as a high-strength reinforcement layer, corrosion-resistant inner and outer layers, or a high-barrier middle layer) in a molten state using a single set of equipment, and extruding them in one step to form functionally composite pipes.
To achieve this goal, the technical key points are closely interlocked:
First and foremost, material design and selection form the foundational cornerstone. It is imperative to scientifically define the functional role of each layer (e.g., corrosion resistance for the inner layer, pressure bearing for the middle layer, and wear resistance for the outer layer), and resolve the issue of interfacial compatibility between different materials with the aid of additives such as compatibilizers. This constitutes the chemical basis for ensuring the pipes do not delaminate during long-term service.
Secondly, precision co-extrusion equipment is the core hardware for realizing this concept, the key of which lies in being equipped with multiple independently controlled extruders and a multi-layer co-extrusion die head hailed as the "heart" of the system. The runner design inside the die head must ensure that the polymer melts of each layer converge accurately at the predetermined positions with uniform pressure, flow rate and temperature. Advanced die heads are also equipped with an independent centering adjustment function to fine-tune the concentricity and wall thickness distribution of the pipes in real time.
Thirdly, precise control of the manufacturing process is the key to translating this technology into high-quality products. This requires the collaborative optimization and stable regulation of the temperature of each extruder (to prevent the degradation of heat-sensitive materials), screw rotation speed (to precisely control the extrusion volume and ratio of each layer), melt pressure, as well as the subsequent vacuum sizing and staged cooling processes. Fluctuations in any single parameter may lead to interfacial disorder and uneven wall thickness.
Finally, modern online inspection and automation systems are important means to ensure production stability and consistency. By integrating ultrasonic thickness measurement, laser outer diameter monitoring and closed-loop feedback systems, real-time monitoring and automatic adjustment of product structures can be achieved, minimizing human error and thus efficiently producing multi-layer composite pipes with regular structures and excellent performance.