Flexible Flat Steel Heating Element for Low-Force Layer Joining

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing contact heating devices for thermally induced material-to-material bonding of flexible material layers face challenges in handling, operational reliability, efficiency, and welding speed, particularly for less experienced users, due to the use of rigid wedge-shaped heating elements that require high mechanical stability and enforce thermal contact with significant force.

Innovation Solution

A contact heating device utilizing a directly powered, flat, planar steel sheet blank as the heating element, which is flexible and adaptable to uneven surfaces, allowing for improved thermal contact, reduced mechanical force, and efficient heat distribution, with features like incisions and extensions for enhanced current distribution and mechanical stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a rigid wedge-shaped heating element is used to enforce thermal contact with material layers, then mechanical stability is improved, but handling difficulty increases and operational reliability decreases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidhandling ease
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The heating element is designed as a flexible flat sheet instead of a rigid wedge, allowing it to adapt to uneven material surfaces and be easily inserted between material layers. This flexible design maintains thermal contact effectiveness while dramatically improving handling ease and reducing the force required for insertion.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The heating element transitions from a static rigid structure to a dynamic flexible structure that can adapt its shape during operation. The flexibility allows the heating element to conform to the material layers it contacts, improving both handling ease and operational reliability across varying material conditions.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If a rigid wedge-shaped heating element is used to enforce thermal contact, then mechanical stability is improved, but the force required for insertion increases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidinsertion force
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The flexible flat sheet design eliminates the need for high insertion force by allowing the heating element to bend and conform to the material layers. The flexibility enables easy insertion between tightly packed material layers without requiring significant mechanical force, while still maintaining stable thermal contact during operation.

Inventive Principle:
Principle #30Flexible shells and thin films

3Stability of the object's composition

If a three-dimensional wedge-shaped heating element is used, then mechanical stability is improved, but adaptability to uneven surfaces decreases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidsurface adaptability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The flexible flat sheet heating element can conform to uneven material surfaces while maintaining stable thermal contact. The flexibility allows the heating element to adapt to surface irregularities, improving adaptability to uneven surfaces while maintaining operational stability through proper contact pressure distribution.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The heating element's dynamic flexibility enables it to adapt to varying surface conditions during operation, improving adaptability to uneven surfaces while maintaining stable thermal contact through continuous conformal contact with the material layers.

Inventive Principle:
Principle #15Dynamics

4Ease of operation

If a flat planar heating element is used instead of a wedge, then handling ease is improved, but mechanical stability may decrease

Engineering Contradiction:
Improvehandling easeVSAvoidmechanical stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The flexible flat sheet design maintains handling ease while achieving mechanical stability through its ability to conform to material surfaces. The flexibility itself becomes a stabilizing factor by ensuring consistent thermal contact, compensating for the lack of rigid wedge structure.

Inventive Principle:
Principle #30Flexible shells and thin films

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 easier handling, improved seam quality, reduced operating costs, and increased operational reliability, enabling rapid temperature control and high welding speeds, while being tolerant to misalignments and contaminants.

Implementation Method 1

a heating element connected between the connection electrodes; wherein the heating element is configured as a directly energized, flat, planar steel sheet blank

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4624139A1Automatic joining device and contact heating device for the thermally induced, cohesive joining of flat, flexible material layers
Publication Date: 2025.10.01 LEISTER TECHNOLOGIES AG
  • EP4624139A1 patent drawingFigure 1~3
  • EP4624139A1 patent drawingFigure 4~5
  • EP4624139A1 patent drawingFigure 6~7

AI summary

The present invention relates to a contact heating device (10) for the thermally induced, material-to-material joining of weldable and/or adhesive-bondable flat, flexible material layers, which are configured as a material web, material strip, and/or material piece and are arranged to at least partially overlap one another, comprising: a first connecting electrode (11) and a second connecting electrode (12); and a heating element (14) connected between the connecting electrodes (11, 12); wherein the heating element (14) is configured as a directly energized, flat, planar sheet steel blank. The present invention further relates to an automatic joining device (1), a handheld device (60), and a method (100).