Coating Solution for Metal Sheet Press Formability
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Solution Overview
Problem
Metal sheets face challenges in press formability during complex forming processes, leading to potential rupture and die galling, and existing lubricating solutions do not adequately address these issues while maintaining antirust properties and film removability.
Innovation Solution
A coating solution containing an acrylic resin with a glass transition point of 100° C. or higher and a polyolefin wax with specific melting and particle size characteristics, along with an antirust agent, is applied to the metal sheets to enhance lubricity and press formability without degrading adhesion or film removability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lubricant oil with high viscosity is used to improve press formability, then the press formability is improved, but the degreasing performance deteriorates and coatability is degraded
Solution Approach 1:
The invention changes the chemical composition parameters of the lubricating film by specifying particular ratios of saturated to unsaturated carboxylic acids (0.3 to 2.0) and controlling total acid content (0.5 to 5.0 mmol/g). This parameter optimization enables the film to provide adequate lubrication during press forming while maintaining compatibility with alkaline degreasing processes, resolving the contradiction between press formability and degreasing performance
Solution Approach 2:
The invention uses a composite lubricating film composed of multiple carboxylic acids with different molecular structures (saturated and unsaturated types) rather than a single substance. This composite composition allows the film to exhibit both good lubricating properties for press forming and good removability by alkaline solutions, thereby resolving the contradiction between these two requirements
2Reliability
If the die is surface-treated to improve press formability, then the press formability is improved, but the die cannot be adjusted after treatment and cost increases
Solution Approach 1:
Instead of treating the die surface to improve press formability, the invention applies a lubricating coating directly to the metal sheet surface. This inversion of the treatment approach allows the sheet to be modified without affecting the die, preserving die adjustability while achieving the desired press formability improvement
3Reliability
If a lubricating film is formed on the metal sheet to reduce sliding resistance, then press formability in cracking-prone areas is improved, but antirust properties and film adhesion must be maintained
Solution Approach 1:
The invention optimizes the acid content parameter of the lubricating film (0.5 to 5.0 mmol/g) to achieve a balance between lubrication performance and rust protection. The controlled acid content provides sufficient lubricity for press forming while maintaining adequate corrosion protection, resolving the contradiction between these two requirements
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 significantly reduces friction coefficients, ensuring excellent press formability, antirust properties, and stable film adhesion, while maintaining film removability during alkaline degreasing, thus addressing the limitations of existing technologies.
Implementation Method 1
a polyolefin wax having a melting point of 100° C. or higher and 145° C. or lower and an average particle diameter of 3.0 μm or less
Implementation Method 2
an acrylic resin having a glass transition point (Tg) of 100° C. or higher and an acid value-to-glass transition point ratio R
Data Source
AI summary
A coating solution for coating a metal sheet to be subjected to complicated forming is disclosed. The coating solution contains an acrylic resin having a glass transition point (Tg) of 100° C. or higher and an acid value-to-glass transition point ratio R=acid value (mg-KOH/g)/Tg (° C.) of 1.50 or more, and a polyolefin wax having a melting point of 100° C. or higher and 145° C. or lower and an average particle diameter of 3.0 μm or less and is applied to a metal sheet.