In-Line Induction Heat Treatment for Low-Distortion Steel Members

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Solution Overview

Problem

Existing methods for hardening and tempering structural members, such as frame rails for heavy trucks, often result in distortions and require large, costly equipment setups with inefficient processes, leading to increased production costs and time due to the need for multiple equipment stations and labor-intensive product transfer.

Innovation Solution

An in-line system and method utilizing rapid induction heating and cooling to produce hardened and tempered structural members with minimal distortions, where a ferrous work piece is roll formed, rapidly heated to austenite, cooled to martensite, and then tempered, allowing for continuous processing and reduced equipment footprint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large furnaces or ovens are used for heating and large tanks for rapid cooling, then the hardening and tempering process can be completed, but the equipment requires a large amount of floor space and is expensive

Engineering Contradiction:
Improvehardening and tempering process completionVSAvoidfloor space requirement
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines multiple processing functions (heating, quenching, tempering) into a single integrated induction heating system with in-line processing stations, eliminating the need for separate large furnaces and cooling tanks that would require extensive floor space

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces traditional mechanical heating systems (large furnaces/ovens) with induction heating technology, which uses electromagnetic fields to heat materials directly and efficiently in a compact footprint, and replaces large liquid cooling tanks with spray quenching systems

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If product is transferred between large equipment stations, then processing can be completed, but the transfer is difficult and labor intensive

Engineering Contradiction:
Improveprocessing completionVSAvoidproduct transfer ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent creates an integrated in-line system where processing stations are connected in sequence, allowing continuous material flow through the system without interruption or manual transfer between separate equipment stations

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent implements continuous in-line processing where the structural member moves continuously through heating, quenching, and tempering stations without interruption, eliminating the need to stop and transfer products between discrete processing stations

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If traditional heating and cooling processes are used, then material properties can be altered, but the process is time consuming and costly

Engineering Contradiction:
Improvematerial property alterationVSAvoidproduction time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces traditional slow thermal conduction heating with induction heating that uses electromagnetic fields to generate heat directly within the material, achieving rapid heating and property alteration in a fraction of the time required by conventional furnaces

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes rapid induction heating to achieve austenitizing temperatures quickly, followed by immediate spray quenching to transform the material microstructure, and then rapid re-heating for tempering, dramatically reducing total processing time while achieving the desired material properties

Inventive Principle:
Principle #35Parameter changes

4Reliability

If multiple equipment stations are used for hardening and tempering, then the process can be completed, but the system requires large floor space and physical transfer of hot metal parts

Engineering Contradiction:
Improvehardening and tempering process completionVSAvoidnumber of equipment stations
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates multiple processing functions (heating, quenching, tempering) into a single unified induction heating system with in-line processing stations, reducing the number of separate equipment stations and simplifying the overall system configuration

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The induction heating system is designed to perform multiple functions (austenitizing heating, tempering heating) using the same basic technology platform, eliminating the need for different types of equipment for different processing steps

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 in-line system efficiently produces structural members with desired hardness and minimal distortions, reducing production time and costs by enabling continuous processing and minimizing the need for post-process correction, while maintaining uniform or varied hardness across zones as required.

Implementation Method 1

rapidly heated a first time in an induction heating device to above a first temperature, thus forming a first metallurgical phase substantially throughout the profiled work piece

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Implementation Method 2

rapidly cooled a first time at a first rapid cooling rate from about the first temperature to a second temperature, thereby converting the first metallurgical phase to a second metallurgical phase

Methodology Applied
Scientific EffectRapid cooling: Cooling

Implementation Method 3

rapidly heated in a second induction heating device a second time to a third temperature, which tempers the hardened work piece

Methodology Applied
Scientific EffectInduction heating: Induction Heating

Data Source

PatentEP3172346B1System and method for producing a hardened and tempered structural member
Publication Date: 2021.09.29 VOESTALPINE METAL FORMING GMBH
  • EP3172346B1 patent drawingFigure 1
  • EP3172346B1 patent drawingFigure 2
  • EP3172346B1 patent drawingFigure 3A~3C

AI summary

System and methods relating to in-line heat-treating, hardening and tempering of material, such as for example, coiled steel into a roll-formed, hardened and tempered structural member having uniform or different targeted properties in selected zones of the structural member. The different targeted properties may be achieved by heating and/or cooling the material subject to certain parameters.