Induction Connection Sleeve With Spring Heating Element

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Solution Overview

Problem

Conventional induction connection sleeves with metal inserts face challenges in ensuring a secure, leak-tight connection between thermoplastic bodies due to production tolerances, requiring external pressure devices to close annular gaps, which is inefficient and complex.

Innovation Solution

An induction connection sleeve with a metallic induction heating element embedded in thermoplastic sockets, prestressed to exert radial pressure during the welding process, ensuring the melted thermoplastic material fills the gap between the socket and the thermoplastic body, eliminating the need for external tensioning devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional induction connection sleeves with metal inserts are used, then induction heating capability is achieved, but external pressure devices are required to close annular gaps caused by production tolerances

Engineering Contradiction:
Improveconnection sealabilityVSAvoidpressure device requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the metal insert and spring element into a single integrated component. The spring element is embedded within the socket structure, merging the induction heating function (metal insert) with the pressure application function (spring) into one unified element, eliminating the need for separate external pressure devices

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The spring element automatically exerts radial pressure on the thermoplastic body during the welding process. This self-service mechanism compensates for production tolerances and annular gaps without requiring external intervention or additional pressure applying devices, making the system self-regulating

Inventive Principle:
Principle #25Self-service

2Ease of manufacture

If production tolerances are large in thermoplastic pipes, then manufacturing cost is reduced, but annular gaps are created requiring special pressure devices

Engineering Contradiction:
Improveproduction toleranceVSAvoidradial pressure device
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The spring element provides automatic pressure compensation that adapts to varying pipe dimensions within tolerance ranges. This self-service mechanism eliminates the need for precision manufacturing or external pressure devices, allowing large production tolerances without compromising connection quality

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The spring element's elastic properties allow it to dynamically adjust the contact pressure parameter based on the actual fit between the pipe and socket. This parameter adaptation compensates for dimensional variations, enabling easy manufacturing without requiring complex pressure control systems

Inventive Principle:
Principle #35Parameter changes

3Strength

If the induction heating element is completely surrounded by thermoplastic material, then structural integrity is improved, but pressure application capability may be reduced

Engineering Contradiction:
Improvestructural integrityVSAvoidradial pressure
Core Design Contradiction:
StrengthVSForce

Solution Approach 1:

The patent merges the structural support function (thermoplastic material surrounding) with the force application function (spring element) into a single integrated design. The thermoplastic material provides structural integrity while the embedded spring element maintains pressure application capability, resolving the contradiction between strength and force

Inventive Principle:
Principle #5Merging (Combining)

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 solution achieves a secure, leak-tight, and strong welded connection without external devices, even with imprecise fits, by using the embedded metallic heating element to press the melted thermoplastic material against the thermoplastic body, effectively closing the annular gap and ensuring a reliable seal.

Implementation Method 1

an induction heating element embedded in the respective sockets... Current flow through the heating element is induced by a primary induction coil placed around the area of the fitting containing the induction heating element

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The temperature of the induction heating element is increased to such an extent that the material of the plastic fitting and the plastic pipe softens and melts

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Implementation Method 3

The induction element is made from a metallic material with spring properties... is prestressed in the opposite direction to the contact pressure required for fusion bonding... presses the melted thermoplastic material against the thermoplastic body

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2172328B1Induction connection sleeve for welding together weldable thermoplastic bodies
Publication Date: 2011.09.28 LEISTER TECHNOLOGIES AG
  • EP2172328B1 patent drawingFigure 1a~1c
  • EP2172328B1 patent drawingFigure 2a~2c
  • EP2172328B1 patent drawingFigure 3~4

AI summary

The sleeve (1) has two sockets (6) for insertion of connection sections (2) of to-be-connected thermoplastic elements (3). An induction heating element (8) is embedded in the sockets. Operative sections of the induction heating element are surrounded completely by a weldable thermoplastic material. The induction heating element is arranged coaxially to the sockets. The induction heating element is made of a metallic material with spring characteristics and placed under pre-tension in the thermoplastic material of the sockets.