Multi-layer plastic pipe with foamed middle layer
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Solution Overview
Problem
Multi-layer plastic pipes require improved mechanical stability and cost-effective material usage for underground applications like sewage and drainage systems, where existing solutions fail to maintain rigidity and resilience, especially in larger diameters.
Innovation Solution
A multi-layer plastic pipe design featuring an inner and outer polyolefin layer with a foamed middle layer comprising 76-85% polyolefin and 15-24% mineral filler, such as talc, glass fiber, or their combination, which reduces density by 10-70% and enhances mechanical properties, allowing for increased rigidity and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wall thickness of the pipe is increased to improve mechanical stability and rigidity, then the radial rigidity and mechanical strength are improved, but the weight and material consumption increase
Solution Approach 1:
The pipe is divided into three distinct layers with different functions: the inner layer provides basic structural integrity, the foamed middle layer provides mechanical cushioning and impact absorption, and the outer layer provides environmental protection and structural support. This segmentation allows each layer to be optimized for its specific function, achieving high radial rigidity without requiring uniform thick walls throughout.
Solution Approach 2:
The middle layer is designed with foamed structure containing air pockets, creating local variations in density and mechanical properties. This foamed structure provides mechanical cushioning and impact absorption where needed, while maintaining overall pipe rigidity. The heterogeneous structure allows the pipe to absorb impacts without requiring uniformly thick walls, reducing overall weight while maintaining strength.
2Strength
If mineral filler is added to the middle layer to improve rigidity and mechanical properties, then the radial rigidity and mechanical strength are improved, but the density and weight increase
Solution Approach 1:
The middle layer uses a composite material consisting of polyolefin combined with mineral fillers (talc, chalk, glass fiber, or wollastonite) in specific weight ratios (76-85% polyolefin and 15-24% mineral filler). This composite provides enhanced rigidity and mechanical strength compared to pure polyolefin, while the foamed structure of the middle layer compensates for weight increase by creating air pockets that reduce overall density.
3Weight of stationary object
If the middle layer is foamed to reduce density and weight, then the material consumption and cost are reduced, but the mechanical stability and rigidity may deteriorate
Solution Approach 1:
The foamed structure creates local variations in density within the middle layer, with air pockets providing mechanical cushioning and impact absorption. This localized heterogeneous structure allows the pipe to absorb impacts and deformations without compromising overall mechanical stability, as the foam structure distributes and absorbs mechanical energy throughout the middle layer.
Solution Approach 2:
The combination of foamed polyolefin with mineral fillers in the middle layer creates a composite material that maintains mechanical stability despite the density reduction from foaming. The mineral fillers provide structural reinforcement within the foamed matrix, ensuring that the middle layer retains sufficient rigidity and mechanical strength while benefiting from the weight reduction of the foamed structure.
4Loss of substance
If larger diameter pipes are produced with thinner wall thickness to reduce material consumption, then the material cost is reduced, but the radial rigidity and mechanical strength may deteriorate
Solution Approach 1:
The three-layer segmented structure allows larger diameter pipes to maintain adequate radial rigidity with thinner overall wall thickness. The foamed middle layer with its cushioning properties and the reinforced composite structure provide mechanical strength distributed throughout the pipe wall, enabling larger diameters to be produced with reduced material consumption while maintaining necessary rigidity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides high radial rigidity, improved mechanical stability, and reduced production costs, enabling the use of larger diameter pipes with smaller wall thicknesses, and extended service life while minimizing material usage and weight, making it suitable for direct underground laying without additional buffering substrates.
Implementation Method 1
The middle layer is foamed in such a way that the density of the middle layer is reduced by 10 to 70% compared to a non-foamed middle layer
Data Source
Figure 1
AI summary
The multilayered plastic pipe has an inner layer (1) that has a polyolefin and a middle layer (3) that is arranged on the inner layer, where an outer layer (2) is arranged on the middle layer. The polyolefin is selected from polyethylene, polypropylene, copolymers of these materials and a combination of these materials.