Cold Rolled Steel Sheet Lubricant Layer for Press Formability
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Solution Overview
Problem
Existing methods for improving the press formability of cold rolled steel sheets, such as surface treatments and high-grade materials, fail to adequately address the issues of steel material fracture and die galling during complex shaping, and often incur high costs or limited improvements.
Innovation Solution
A cold rolled steel sheet with a specific binder and natural wax composition, applied as a layer with a controlled mass ratio and pH, which enhances lubrication properties and allows for excellent press formability while maintaining weldability and alkali layer-removability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface treatment is performed on a press mold to improve press formability, then press formability is improved, but the press mold cannot be adjusted after treatment and costs increase
Solution Approach 1:
The invention introduces a lubricant layer as an intermediary substance between the steel sheet and the press mold. This lubricant layer, containing specific compounds like fatty acids and metal soaps, mediates the interaction during press forming, reducing direct contact and friction. This resolves the contradiction by improving press formability through the lubricant layer rather than through permanent mold surface treatment, thereby maintaining mold adjustability and reducing costs.
Solution Approach 2:
The invention changes the chemical composition parameters of the lubricant layer by specifying particular compounds (fatty acids with specific carbon chain lengths, metal soaps with specific metal content). By optimizing these chemical parameters, the lubricant layer achieves optimal press formability without requiring permanent modifications to the mold surface, thus maintaining ease of manufacture and adjustability.
2Reliability
If high-grade materials with excellent material properties are used to improve press formability, then press formability is improved, but costs increase and there is a limit to improvement
Solution Approach 1:
Instead of relying solely on high-grade steel materials, the invention introduces a lubricant layer as an intermediary that actively improves press formability during the forming process. This lubricant layer, containing optimized combinations of fatty acids and metal soaps, provides the necessary lubrication and surface properties without requiring expensive high-grade base materials, thereby reducing costs while achieving excellent press formability.
Solution Approach 2:
The invention creates a composite structure consisting of the base steel sheet combined with a lubricant layer containing multiple components (fatty acids, metal soaps, and other additives). This composite approach allows the use of standard-grade base materials while achieving superior press formability through the functional lubricant layer, avoiding the need for expensive high-grade materials.
3Reliability
If a layer is formed on the steel sheet to improve press formability, then press formability is improved, but subsequent processes like welding and coating may be interfered with
Solution Approach 1:
The invention carefully controls the chemical composition parameters of the lubricant layer, specifying particular fatty acids (with carbon chain lengths of 12-22) and metal soaps (with specific metal content ranges). These parameter optimizations ensure that the lubricant layer provides sufficient press formability while maintaining compatibility with subsequent welding and coating processes, as the controlled composition allows for effective layer removal and does not interfere with material bonding.
Solution Approach 2:
The lubricant layer is designed with specific local properties: it provides high lubrication during press forming, then can be effectively removed by alkali treatment before welding and coating. The localized application of this controlled-composition layer ensures excellent press formability where needed while maintaining adaptability to subsequent processes through proper removal and surface preparation.
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 steel sheet achieves improved press formability, reduced friction, and effective layer removal, suitable for automotive applications without interfering with subsequent processes like welding and coating.
Implementation Method 1
where water is a main solvent and the pH of the aqueous agent is 7 or more and 12 or less
Data Source
Figure 1
Figure 2~3
AI summary
Provided is a cold rolled steel sheet with excellent press formability, which contains a binder satisfying specific requirements and wax satisfying specific requirements, and has a layer containing the wax in a specific mass ratio at a specific coating weight.