Multi-Steel Door Ring With Overlap Welding and Corrosion Protection
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Solution Overview
Problem
Existing door rings in motor vehicle bodies lack improved strength properties and corrosion protection while maintaining favorable manufacturability.
Innovation Solution
A door ring composed of interconnected components made from varying grades of steel, including ultra-high-strength manganese-boron steel and conventional steel, with a corrosion protection layer and laser-welded overlap joints, ensuring tensile strengths above 1300 MPa and effective corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional steel grades are used for door ring components, then manufacturing cost and ease of manufacture are improved, but tensile strength is insufficient (below 1300 MPa)
Solution Approach 1:
The patent applies different steel grades to different components based on their specific strength requirements. High-strength steel (≥1300 MPa) is used for critical components like the A-pillar and B-pillar where strength is paramount, while conventional steel is used for less critical components. This local differentiation resolves the contradiction by providing necessary strength where needed without unnecessarily complicating manufacturing across all components.
Solution Approach 2:
The door ring is constructed as a composite structure combining multiple steel grades. The heterogeneous material composition allows the structure to achieve overall high strength properties while maintaining manufacturing feasibility through the use of conventional materials in appropriate locations. The laser welding process successfully joins these different material types.
2Strength
If ultra-high-strength steel is used for all components, then tensile strength above 1300 MPa is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of uniformly applying ultra-high-strength steel to all components, the patent implements a differentiated approach where only critical load-bearing components (A-pillar, B-pillar) use steel with tensile strength ≥1300 MPa. Non-critical components use conventional steel grades, thereby reducing overall structural complexity and manufacturing difficulty while maintaining necessary strength levels.
3Manufacturing precision
If laser welding is used to join components with different steel grades, then manufacturing precision and productivity are improved, but corrosion protection integrity may be compromised
Solution Approach 1:
The corrosion protection layer is applied to the components before the laser welding process. This preliminary coating ensures that the base metal is protected during welding, and the welding parameters are optimized to minimize damage to the pre-applied corrosion protection layer. After welding, the corrosion protection is restored in the heat-affected zone, maintaining integrity throughout the joint.
4Strength
If multiple steel grades are combined in the door ring, then optimized strength properties are achieved, but manufacturing complexity increases
Solution Approach 1:
The patent implements a strategic distribution of different steel grades to specific components based on their functional requirements. The A-pillar and B-pillar use high-strength steel for crash resistance, while other components use conventional steel. This localized material selection optimizes overall strength while keeping manufacturing processes manageable through clear material-zoning.
Solution Approach 2:
The patent replaces traditional mechanical joining methods with laser welding technology. This substitution enables precise joining of different steel grades with controlled heat input, minimizing distortion and simplifying the manufacturing process despite the complexity of joining heterogeneous materials. The laser welding process provides automated, high-precision joining that reduces manual intervention.
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 enhanced strength and corrosion protection, with tensile strengths up to 2200 MPa and robust corrosion resistance, while maintaining efficient manufacturing processes.
Implementation Method 1
a corrosion protection layer is present on the components coupled to the door ring, in particular also in the overlap area
Implementation Method 2
at least two of the individual components are laser-welded to one another with an overlap area
Implementation Method 3
a hardenable steel, such as a manganese-boron steel, which is formed by hot forming and press hardening
Implementation Method 4
formed by hot forming and press hardening
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a door ring (1) for a motor vehicle body comprising individual coupled components in the form of an A-pillar (2), a B-pillar (4), a roof frame part (3) and a sill part (5), wherein at least in one area a tensile strength Rm greater than 1300 MPa is formed and in another area a tensile strength Rm less than 1000 MPa is formed, wherein the door ring (1) has a corrosion protection layer, characterized in that the components are laser-welded with an overlap, in particular an overlap joint, and that the corrosion protection layer is formed between the overlapping layers (9, 11).