Composite Pipe Adhesion via Compressive Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for manufacturing multilayer composite pipes with plastic and metal layers face challenges in achieving reliable and even welding seams, as the tie layer is under constant tensile stress, leading to potential breaks during pipe expansion, and the metal layer's high temperature can damage the plastic core, while also causing hardening of the product.
Innovation Solution
A method involving the formation of a core with a plastic outer surface, extrusion of a seamless metal layer with a larger inner diameter to avoid initial contact, followed by cooling and application of an adhesive action with a permanent compressive force to ensure strong adhesion between the core and metal layer, using foaming agents or materials with memory effects to maintain contact without tensile stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the metal layer is pressed directly on the plastic core at high temperature, then the metal layer adheres to the core, but the plastic core is damaged by melting
Solution Approach 1:
A mandrel with internal cooling shroud is introduced as an intermediary between the hot metal layer and the plastic core. The cooling shroud circulates cooling medium to maintain the core's temperature while allowing metal extrusion, preventing thermal damage to the plastic core while enabling adhesion.
Solution Approach 2:
The temperature parameter of the core is dynamically controlled by the cooling system during the metal extrusion process. The core temperature is maintained below the melting point of plastic while the metal layer is extruded at high temperature, resolving the contradiction between adhesion requirements and core protection.
2Manufacturing precision
If the metal tube is drawn or swagged down to eliminate space between core and pressed metal, then tight cladding is achieved, but the product becomes work-hardened and difficult to manipulate
Solution Approach 1:
The mechanical drawing or swaging process is replaced by a chemical adhesion system. An adhesive layer is applied between the core and metal layer, allowing tight bonding without mechanical deformation. This eliminates work-hardening while achieving the desired contact and structural integrity.
3Strength
If the tie layer is used to bond plastic layers with metal layer, then adhesion is achieved, but the tie layer remains under constant tensile forces leading to breaks during pipe expansion
Solution Approach 1:
The problematic tie layer is completely removed from the structure. Instead of using a separate adhesive layer that is prone to tensile stress and breakage, the invention relies on the inherent adhesion between the core and metal layer achieved through controlled cooling and contact, eliminating the weak link in the system.
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
This approach results in a robust and long-lasting composite pipe with improved adhesion between layers, reducing the risk of breaks and maintaining flexibility while avoiding metal hardening, ensuring excellent long-term properties.
Implementation Method 1
cooling the metal layer
Implementation Method 2
arranging an adhesive action between the core and the metal layer
Implementation Method 3
arranging a permanent compressive force for compressing the core and the metal layer together
Data Source
Figure 1~2
Figure 3
AI summary
An elongated product is formed such that first a core is formed, the outer surface of the core being made of plastic. Thereafter, a tubular metal layer is extruded such that the layer is seamless. When the metal layer is extruded, a clearance (16) is allowed between the metal layer and the core. After the metal layer has cooled, the outer surface of the core is arranged against the inner surface of the metal layer. An adhesive action is arranged between the core and the metal layer and a permanent compressive force is arranged, which compressive force compresses the core and the metal layer together.