Development and design process of large-diameter double-wall corrugated pipe production line
With the continuous and rapid development of China's national economy, the scale of urban construction is also expanding. Drainage/sewage pipes are an important part of the municipal pipe network system, and their performance will directly affect the reliability and safety of the sewage discharge system. The elimination of concrete pipes, even cast iron pipes, ceramic fired pipes, etc. is the general trend. Developed countries have legally prohibited the use of these seriously polluting pipes, and China will also be in line with international standards. PE-HD double-wall corrugated pipes have occupied an increasing market share in drainage/sewage due to their own unique advantages.
PE-HD double-wall corrugated pipe was first successfully developed in Germany in the early 1980s. After nearly two decades of development and improvement, it has developed from a single variety to a complete product series. PE-HD double-wall corrugated pipe started late in China, but it has been popularized and applied very quickly. At present, there are hundreds of domestic manufacturers producing this kind of pipe.
In recent years, the development trend of double-wall corrugated pipes is to pursue large diameters. Among them, UNICOR claims that their PE-HD double-wall corrugated pipes can achieve an outer diameter of 2400 mm, and there is currently no equipment capable of producing such large pipe diameters in China. Large-diameter molding equipment reflects the R&D capabilities and manufacturing technology of equipment manufacturers. For domestic equipment suppliers, the molding equipment for manufacturing large-diameter double-wall corrugated pipes also requires extrusion systems, extrusion dies, and corrugated molding systems. Update the design concept and truly master the ring stiffness calculation method of the double-wall corrugated pipe production line to optimize the pipe wall structure.
At present, the standard configuration of PE-HD double-wall corrugated pipe production line generally uses two high-efficiency single-screw extruders with a length-to-diameter ratio of 33:1. The so-called "high efficiency" means that the output is higher than that of the traditional single screw extruder, and the improvement of the material mixing capacity is not the original design goal of this type of extruder. For double-wall corrugated pipes, as the diameter increases, the pipe meter weight will rise rapidly, which will reduce the cost advantage of double-wall corrugated pipes compared to other traditional drainage pipes. For this reason, it is particularly urgent for large-diameter double-wall corrugated pipes to make necessary modifications to the raw material of the corrugated pipe to increase its elastic modulus and to reduce the meter weight. As we all know, the advantages of the traditional single-screw extruder are more reflected in the simple structure and high extrusion pressure, while its mixing ability is relatively weak. For this reason, people have been trying to improve the screw configuration in order to ensure the traditional advantages. On the basis of improving its mixing performance, although certain progress has been made, it is still far from people's expectations.
In terms of plastic modification, people rely more on co-rotating twin-screw extruders and BUSS mixers. Due to the unsatisfactory mixing performance of the single-screw extruder, it is now common practice to mix and pelletize on the same-rotating twin-screw extruder, and then extrude with a single-screw extruder, which obviously increases energy consumption and improves The cost of the final product. If mixing and extrusion can be completed on one extruder at the same time, the production process will be simplified and the product cost will be reduced. For this reason, researchers must have a deep understanding of extrusion theory, be able to cleverly combine the characteristics of the current mixing and extrusion extruders, and give a completely new set of screw design concepts that are completely different from the existing ones. Realize that an extruder has both the mixing effect of a co-rotating twin-screw extruder and the extrusion capacity of a single-screw extruder. Based on this guiding ideology, Dingsu-tech is making some useful attempts. The prototype is currently being developed and will be available soon.