Inductive Reheating for Hot-Forming Energy and Crack Reduction

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Solution Overview

Problem

Conventional methods for producing high-strength components using hot forming are inefficient due to the high energy requirements of continuous furnaces, inability to target specific heating, and the risk of hydrogen-induced stress corrosion cracking, which leads to delayed crack formation and increased operational costs.

Innovation Solution

A method that integrates inductive heating devices between processing stations in a production line to reheate workpieces selectively, reducing energy consumption and internal stresses, allowing for precise temperature control and flexible production line design, thereby minimizing hydrogen-induced stress corrosion cracking and optimizing material properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a continuous furnace is used to heat the workpiece before hot forming, then the workpiece can be heated to the required temperature, but the energy consumption is high and the furnace occupies large space

Engineering Contradiction:
Improveworkpiece temperatureVSAvoidenergy consumption
Core Design Contradiction:
TemperatureVSUse of energy by stationary object

Solution Approach 1:

The continuous furnace is divided into multiple individual heating devices arranged between processing stations. Each heating device independently heats workpieces at specific locations along the production line, replacing the single large-scale continuous furnace and reducing overall energy consumption.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Heating is applied locally at specific processing stations where it is most needed, rather than heating the entire workpiece continuously through a long furnace. This localized approach reduces energy waste and allows for targeted temperature control at each station.

Inventive Principle:
Principle #3Local quality

2Temperature

If a continuous furnace is used for heating, then the workpiece can be heated uniformly, but the furnace requires large space and can only be arranged in front of the press line

Engineering Contradiction:
Improveworkpiece temperatureVSAvoidfurnace space
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The continuous furnace is segmented into multiple discrete heating devices that can be distributed throughout the production line. This allows the heating function to be integrated into the existing press line layout without requiring a large separate furnace space in front of the line.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating function is transitioned from a single large spatial structure (continuous furnace) to multiple distributed heating points arranged along the production line in the material flow direction, effectively utilizing the longitudinal dimension of the press line.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Temperature

If the workpiece is heated in a continuous furnace, then the workpiece can be heated to forming temperature, but hydrogen-induced stress corrosion cracking may occur due to hydrogen diffusion in high-strength materials

Engineering Contradiction:
Improveworkpiece temperatureVSAvoidcrack resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The continuous heating process is divided into multiple separate heating zones between processing stations. This allows for controlled heating cycles with intermediate cooling phases, reducing continuous hydrogen exposure time and minimizing hydrogen diffusion into the high-strength material.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The heating process is applied periodically at discrete stations rather than continuously. Workpieces undergo intermittent heating cycles with cooling periods in between, which reduces the total time for hydrogen diffusion and lowers the risk of hydrogen-induced stress corrosion cracking.

Inventive Principle:
Principle #19Periodic action

4Temperature

If conventional heating devices are used to prevent excessive cooling, then the workpiece can be maintained at temperature, but the floor-based transport method and installation effort are required

Engineering Contradiction:
Improveworkpiece temperatureVSAvoidinstallation complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The heating devices are integrated into the existing production line infrastructure and automatically heat workpieces during their normal transport and processing. The system utilizes the existing material flow and processing sequence, requiring no separate transport infrastructure or complex installation.

Inventive Principle:
Principle #25Self-service

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 reduces energy consumption, minimizes hydrogen-induced stress corrosion cracking, and allows for precise temperature control, resulting in more efficient and flexible production of high-strength components with reduced internal stresses and operational costs.

Implementation Method 1

A method that integrates inductive heating devices between processing stations in a production line to reheate workpieces selectively

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The workpiece is at least partially reheated in order to improve its ability to change shape and/or reduce its strength in preparation for the further manufacturing process by means of at least one heating device arranged between processing stations

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Data Source

PatentEP2414551B1Process for producing a component, in particular a vehicle body part, and production line for carrying out the process
Publication Date: 2020.12.02 AUDI AG
  • EP2414551B1 patent drawingFigure 1
  • EP2414551B1 patent drawingFigure 2

AI summary

The invention relates to a process for producing a component, in particular a vehicle body part, in which process a workpiece (10) passes through a plurality of production stages in order to produce the component and a production process is carried out in each production stage, and the workpiece (10) is fed to a machining station for carrying out each production process in order to perform each production stage, wherein at least one of the production processes involves hot-forming of the workpiece (10), for which purpose the workpiece (10) is subjected to a first, at least partial heating operation, and at least one further production process is carried out on the workpiece (10) after the hot-forming step. Provision is made for the hot-forming to be followed by at least partial reheating of the workpiece (10) by means of at least one heating device (41, 42, 43) arranged between machining stations in the production process sequence in order to improve the deformability of said workpiece and/or to reduce the strength in preparation of the further production process. The invention also relates to a production line for producing a component, in particular a vehicle body part, which is suitable in particular for carrying out the process according to the invention.