Blank Preheating for Homogeneous Hot Stamping Furnace Heating

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Solution Overview

Problem

In hot stamping production lines, blanks with varying thicknesses or materials are not homogeneously heated, leading to inadequate deformation and potential breakage during processing, due to insufficient temperature gradients, which can result in incomplete microstructure transformation and material property changes, necessitating longer furnace lengths and increased processing times.

Innovation Solution

A preheating system is introduced to raise the temperature of blanks, particularly the thickest zones, before entering the furnace, using retractable pins or elevating bars to retain the blanks at a preheating location, allowing for rapid heating to temperatures between 300-820 °C, reducing the time in the furnace and ensuring homogeneous heating upon exit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If blanks with varying thicknesses or materials are heated in a conventional furnace, then the heating process can be simplified, but the heating becomes non-homogeneous leading to inadequate deformation and potential breakage

Engineering Contradiction:
Improveheating homogeneityVSAvoidblank integrity during deformation
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-heating the blank to a first temperature (e.g., 50-200°C) before the main heating stage in the furnace. This preliminary heating ensures that even thick zones start with a baseline temperature, enabling more uniform subsequent heating and preventing thermal gradients that would cause deformation failures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements local quality by applying different heating temperatures to different zones of the blank. Specifically, at least the thickest zone is heated to a second temperature (higher than the first temperature), while other zones are heated to the first temperature. This localized differential heating compensates for the varying thermal mass and ensures homogeneous overall heating.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If furnace length is increased to ensure homogeneous heating of blanks with varying thicknesses, then heating homogeneity improves, but production space and processing time increase

Engineering Contradiction:
Improveheating homogeneityVSAvoidprocessing cycle time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

By performing preliminary heating before the main furnace processing, the patent reduces the time required in the furnace to achieve homogeneous heating. This two-stage approach allows for shorter furnace residence time while maintaining heating quality, thereby improving productivity without sacrificing heating homogeneity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the heating parameters by implementing a two-temperature regime: a first temperature for general zones and a second, higher temperature for thickest zones. This parameter differentiation allows for optimized heating cycles that achieve homogeneous heating faster, reducing the required furnace length and processing time.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If conventional heating is used for thick zones, then equipment complexity remains low, but heating time and energy consumption increase

Engineering Contradiction:
Improveheating system complexityVSAvoidfurnace energy consumption
Core Design Contradiction:
Device complexityVSUse of energy by stationary object

Solution Approach 1:

The patent applies local quality by directing higher heating temperatures specifically to the thickest zones of the blank, while maintaining lower temperatures in thinner zones. This localized energy application reduces overall energy consumption by avoiding excessive heating of areas that require less thermal input, while still achieving homogeneous heating of the entire blank.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By implementing variable temperature parameters across different zones of the blank, the patent optimizes energy distribution. The system uses a first temperature for most zones and a second, higher temperature only where needed (thickest zones), thereby reducing total energy consumption compared to uniform high-temperature heating, while maintaining heating effectiveness.

Inventive Principle:
Principle #35Parameter changes

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 the length of the furnace, decreases energy consumption and space requirements, maintains temperature consistency, and prevents contamination of conveyor system components, while optimizing the heating process without adding extra time to the overall manufacturing cycle.

Implementation Method 1

preheating system is introduced to raise the temperature of blanks, particularly the thickest zones, before entering the furnace

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

a furnace system heats steel blanks at a predetermined temperature, e.g. above an austenization temperature, particularly above Ac3

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 3

the blanks are transferred to a press system which deforms the blanks to the shape of the end product

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 4

blanks may need to be quenched, i.e. be cooled down rapidly from a high temperature to a low temperature, to achieve a high tensile strength

Methodology Applied
Scientific EffectRapid cooling: Cooling

Data Source

PatentEP3559283B1Method for heating a blank and heating system
Publication Date: 2024.11.27 AUTOTECH ENG SL
  • EP3559283B1 patent drawingFigure 1~2a
  • EP3559283B1 patent drawingFigure 2b~2c
  • EP3559283B1 patent drawingFigure 2d

AI summary

A method for manufacturing a steel component from a blank is provided. Firstly,a blank is placed in a conveyor system. Then, at least a preselected zone of the blank is preheated while the blank is retained at a predetermined preheating location. Finally,the blank is conveyed through a furnace.A preheating system for heating blanks in a production line is also provided.