Electrofusion Joint Heating Layout for Smooth Inner Pipe Fusion
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Solution Overview
Problem
Electrofusion joints used in connecting resin pipes suffer from issues such as clevis and convex portions (wrinkles) on the inner surface due to uneven heating and resin deformation, leading to water and chemical solution retention, microbial growth, and reduced product yield.
Innovation Solution
The electrofusion joint design includes a main body with a stopper portion and two heat generating sections, where the first heat generating section has a lower heating wire density and fewer turns than the second, ensuring even heating and preventing early fusion on the side surface, while the second heat generating section has multiple turns to ensure complete fusion and stable bead formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the stopper portion is made thin to reduce material usage, then the amount of resin is reduced, but the stopper portion is deformed by the force of abutting the resin pipe and convex portions (wrinkles) are generated
Solution Approach 1:
The heating wire density is made non-uniform in the stopper portion, with higher density at the outer peripheral side and lower density at the inner peripheral side. This local variation in heating intensity allows the outer peripheral region to provide sufficient heating pressure to prevent wrinkle formation, while the inner peripheral region uses less heating to avoid excessive resin flow and deformation.
2Strength
If the stopper portion is made thick to prevent deformation, then the stopper portion maintains structural integrity, but the heating with the heating wire is insufficient and clevis is generated
Solution Approach 1:
The heating wire density varies locally within the stopper portion, with higher density at the outer peripheral side to provide intensive heating for adequate fusion, and lower density at the inner peripheral side to prevent excessive heating. This local differentiation allows the stopper portion to be sufficiently thick for structural integrity while achieving proper fusion quality through targeted heating zones.
3Reliability
If heating wire density is increased to ensure complete fusion, then fusion is more complete, but the side surface fuses too early and convex portions (wrinkles) are generated
Solution Approach 1:
The heating wire density is differentiated by location: higher density at the outer peripheral side of the stopper portion ensures complete fusion at the critical interface, while lower density at the inner peripheral side prevents premature fusion and wrinkle formation. This spatial variation in heating intensity resolves the contradiction between fusion completeness and surface smoothness.
4Manufacturing precision
If heating wire density is decreased to prevent early fusion, then wrinkle formation is reduced, but fusion is insufficient and clevis is generated
Solution Approach 1:
By implementing non-uniform heating wire density with higher concentration at the outer peripheral side and lower concentration at the inner peripheral side, the system achieves both goals: the outer region provides sufficient heating for complete fusion without clevis, while the inner region maintains lower heating to prevent premature fusion and wrinkle formation.
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 design effectively suppresses the occurrence of clevis and convex portions, ensuring stable fusion and reducing the force required for pipe insertion, thereby preventing water and chemical solution retention and microbial growth.
Implementation Method 1
a heating wire that is wound and arranged at the joint receiving portion... a heating wire is wound so that wound parts are adjacent to each other and the heating wire is disposed in the stopper portion
Implementation Method 2
the resin on the inner peripheral part of the insertion openings and the resin on the outer peripheral part of the pipe are fused around the heating element
Data Source
AI summary
An electrofusion joint includes a tubular main body, a stopper portion, a first heat generation section, and a second heat generation section. The tubular main body includes a joint receiving portion. The stopper portion projects inwardly on an inner surface of the tubular main body. The first heat generation section includes a first heater wire wound and arranged at the joint receiving portion. The second heat generation section includes a second heater wire wound so that wound parts of the second heater wire are adjacent to each other and the second heater wire is in the stopper portion. The first heat generation section includes at least one heat generation portion in which the first heater wire is wound so that wound parts of the first heater wire are adjacent to each other.