Press-Hardened Door Ring With Variable Thickness and Local Strength
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Solution Overview
Problem
Existing methods for producing press-hardened door rings for motor vehicles do not efficiently meet regionally or locally different strength requirements, often resulting in unnecessary sheet metal waste and complex joining processes.
Innovation Solution
A method involving a flexibly rolled steel sheet material with varying thicknesses and strengths, where the sheet is heated and formed into a one-piece door ring using press hardening, allowing for different material structures and mechanical characteristics to be achieved through controlled heating and cooling, eliminating the need for additional reinforcements and reducing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a door ring is manufactured as a single sheet metal part, then manufacturing time is reduced and joining processes are eliminated, but different strength requirements in different areas cannot be met
Solution Approach 1:
The patent applies local quality by creating a blank with spatially varying sheet thicknesses through flexible rolling before press hardening. The blank has different thicknesses in different areas (e.g., thicker in reinforcement zones, thinner in non-critical areas), which directly translates to different strengths after hardening. This eliminates the need for separate reinforcement parts and joining processes while meeting localized strength requirements.
Solution Approach 2:
The patent changes the physical parameter of sheet thickness in the blank before press hardening using flexible rolling technology. By varying the thickness parameter across different areas of the blank, the final door ring achieves different strengths after hardening without requiring additional parts or assembly steps.
2Strength
If reinforcement parts are added to meet strength requirements, then different strength requirements are satisfied, but manufacturing complexity and joining processes increase
Solution Approach 1:
The patent merges the reinforcement function directly into the main door ring blank by creating variable thickness zones in the blank before press hardening. This eliminates the need for separate reinforcement parts and their associated joining processes (welding, bonding, or mechanical fastening), thereby reducing manufacturing complexity while satisfying strength requirements.
Solution Approach 2:
The patent extracts the reinforcement concept from separate parts and integrates it into the blank's geometry itself. Instead of adding reinforcement elements, the blank is designed with varying thicknesses that provide reinforcement where needed, taking out the need for additional components and simplifying the overall manufacturing process.
3Ease of manufacture
If uniform sheet thickness is used, then manufacturing is simpler, but weight optimization and crash performance are compromised
Solution Approach 1:
The patent applies local quality by creating spatially varying sheet thicknesses in the blank before press hardening. Thicker sections are placed in crash-relevant areas for improved performance, while thinner sections are used in non-critical areas for weight reduction. This localized differentiation optimizes both weight and crash performance without significantly complicating manufacturing.
4Strength
If separate reinforcement parts are manufactured and joined, then strength requirements are met, but tolerance issues and manufacturing time increase
Solution Approach 1:
The patent merges the reinforcement functionality into the main door ring blank, eliminating separate parts and their associated joining operations. This removes the source of tolerance accumulation that occurs during multiple joining steps, ensuring better dimensional accuracy and reducing manufacturing precision issues while still meeting strength requirements through variable thickness design.
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 enables the cost-effective and robust production of a one-piece press-hardened door ring with optimized strength and crash performance, minimizing weight and error susceptibility while eliminating the need for complex joining processes.
Implementation Method 1
a steel sheet suitable for press hardening is heated to austenitizing temperature and formed in a cooled die (press hardening die) while simultaneously being cooled. This process results in an increase in hardness and/or strength due to a martensitic hardening effect
Implementation Method 2
a steel sheet suitable for press hardening is heated to austenitizing temperature and formed in a cooled die (press hardening die) while simultaneously being cooled. This process results in an increase in hardness and/or strength due to a martensitic hardening effect
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for manufacturing a one-piece press-hardened door ring (200) for a motor vehicle, which has different sheet thicknesses (D1, D2, D3) and strengths (F1, F2), comprising: - providing a flexibly rolled steel sheet material (S) having different sheet thicknesses (D1, D2, D3) in certain areas; - producing a blank from the flexibly rolled steel sheet material (S), wherein the blank has at least one door opening cutout; - heating the blank; - inserting the heated blank into a press-hardening tool and carrying out a press-hardening process in which the door ring (200) is formed into the intended final geometry and hardened differently in certain areas.