Contact-Cooling Press for Localized Yield Point Control
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Solution Overview
Problem
Existing press-hardening methods fail to efficiently create geometrically well-defined areas with a lower yield point and ultimate tensile strength in press-hardened products, often resulting in inconsistent cooling and increased tool wear.
Innovation Solution
A press-hardening plant with a contact cooling process that rapidly cools selected parts of the sheet-steel blank to promote ferrite growth before the press-hardening operation, using a contact-cooling press situated between the furnace and the press-hardening press, allowing for controlled ferrite formation and reduced hardness in specific areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If selected portions are cooled by air blowing before press-hardening, then softer portions are obtained, but the cycle time increases and temperature control precision deteriorates
Solution Approach 1:
The patent replaces air blowing (aerodynamic cooling) with direct contact cooling using a cooling plate. This mechanical contact system provides more efficient and faster heat extraction from the steel blank, achieving the desired softer portions with reduced cycle time compared to air cooling methods.
Solution Approach 2:
The patent introduces a cooling plate as an intermediary element between the steel blank and the cooling system. This mediator enables controlled thermal exchange at specific locations, allowing precise temperature reduction in selected portions during the heating phase, thereby creating softer areas without extending the overall process time.
2Loss of time
If cooling plates are used for contact cooling, then cycle time is reduced, but tool wear increases
Solution Approach 1:
The cooling plates are positioned to contact only specific selected portions of the steel blank, not the entire surface. This localized cooling approach concentrates the thermal action where needed while minimizing contact between the cooling plates and the blank in other areas, thereby reducing overall tool wear while maintaining fast cooling performance.
3Stability of the object's composition
If heating is applied to achieve austenitising temperature, then uniform microstructure is obtained, but softer portions cannot be created
Solution Approach 1:
The patent applies cooling plates to selected portions of the steel blank during the heating phase, before the press-hardening operation begins. This preliminary localized cooling creates temperature differences and initiates different microstructural transformations in selected areas versus the rest of the blank, enabling softer portions to be created while the blank is still being heated to austenitising temperature.
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 method enables the production of products with well-defined, softer portions and reduced hardness, while minimizing tool wear and achieving a short cycle time with improved reproducibility and control over ferrite formation.
Implementation Method 1
selected parts of the blank are contact-cooled to a temperature which promotes ferrite growth during the subsequent transfer to the press-hardening press and during the press-hardening operation
Implementation Method 2
after the blank has been heated to the austenitising temperature, selected parts of the blank are contact-cooled to a temperature which promotes ferrite growth
Data Source
AI summary
In a press-hardening plant, a contact-cooling press (12) is provided between the furnace (11) and the press-hardening press (13). Preselected parts of the blank (18) are contact-cooled such that corresponding parts of the finished product are softer and display a lower yield point.