Press-Hardened Sheet Metal with a Controlled Crash Breaking Point
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Solution Overview
Problem
Press-hardened sheet metal components in motor vehicles exhibit high strength but low ductility, leading to uncontrolled fractures and sharp edges during accidents, limiting their ability to absorb collision energy effectively.
Innovation Solution
A press-hardened sheet metal component with an overhardened area of high strength and low ductility is created during the press hardening process, serving as a predetermined breaking point to redirect collision energy, eliminating the need for additional heat treatments and allowing for targeted energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press hardening is applied to increase strength, then tensile strength increases to 1300 MPa and more, but ductility decreases significantly leading to uncontrolled fractures
Solution Approach 1:
The patent applies local quality by creating an overhardened area with distinct material properties (higher hardness, lower ductility) at a specific location within the sheet metal component. This localized modification allows the component to have different mechanical properties in different regions, enabling controlled fracture behavior while maintaining overall structural integrity.
Solution Approach 2:
The overhardened area is created in advance during the press hardening process through localized intensified cooling. This preliminary action prepares a predetermined breaking point before any crash load occurs, ensuring that when deformation happens, it occurs at the intended location rather than causing uncontrolled fractures elsewhere.
2Loss of energy
If press hardening is applied to increase strength, then collision energy absorption capacity is limited, but manufacturing complexity increases when attempting to improve energy absorption
Solution Approach 1:
The patent changes the material parameters (hardness, ductility) through controlled variation of cooling conditions during press hardening. By adjusting cooling intensity and duration in specific areas, the overhardened zone is created without requiring additional manufacturing steps, thus improving energy absorption capacity while avoiding increased manufacturing complexity.
3Loss of energy
If additional heat treatments are applied to create different structural areas, then energy absorption improves, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges the heat treatment function into the existing press hardening process by implementing localized intensified cooling. This combination eliminates the need for separate post-press-hardening heat treatment steps, achieving the desired overhardened area while avoiding additional manufacturing complexity and cost.
Solution Approach 2:
The press hardening tool itself performs the heat treatment function through its cooling system. The cooling device is designed to provide localized intensified cooling during the normal press hardening cycle, allowing the process to create the overhardened area without requiring external or additional treatment equipment.
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 component effectively manages crash loads by tearing or fracturing at the overhardened area, redirecting energy to adjacent components for absorption, enhancing safety by controlling deformation and reducing injury risks.
Implementation Method 1
the steel sheet material is heated to the austenitizing temperature and then formed in a press hardening tool and rapidly cooled at the same time, which results in significant increases in strength
Implementation Method 2
rapidly cooled at the same time
Data Source
Figure 1~2
AI summary
The invention relates to a sheet-metal component (120) composed of a press-hardened steel-sheet material (M), in particular a motor vehicle body component which has at least one overaged component region (125) which is provided to act as a predetermined breaking point under a crash loading (F). The invention furthermore relates to a component assembly and a motor vehicle body, which have at least one such press-hardened sheet-metal component (120).