Press Formed Part Shape Prediction Under Residual Stress Relaxation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current press forming simulations struggle to accurately predict the shape change of press formed parts over time due to springback, especially for high-strength metal sheets, as they do not account for residual stress relaxation and its impact on shape change after the part is released from the die.
Innovation Solution
A method that includes acquiring the shape and residual stress immediately after springback, setting reduced residual stress values in bent portions, and analyzing the resulting shape balance to predict long-term shape changes, focusing on punch and die shoulders in press formed parts made from high-strength metal sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a press forming simulation using finite element method is used to predict shape change, then the prediction can be performed systematically, but the shape prediction accuracy is low for certain press formed parts
Solution Approach 1:
The patent divides the prediction process into two stages: first performing a press forming analysis to obtain residual stress distribution, then using this residual stress as input for a springback analysis. This segmentation allows each stage to be optimized independently, improving overall prediction accuracy while maintaining systematic efficiency.
Solution Approach 2:
The patent performs press forming analysis before springback analysis to pre-calculate the residual stress distribution. This preliminary action provides accurate initial conditions for the subsequent springback prediction, resolving the accuracy issue while maintaining computational efficiency.
2Strength
If high-strength metal sheet is used for press forming, then weight reduction and collision safety are improved, but dimensional accuracy deteriorates due to increased springback
Solution Approach 1:
The patent uses the residual stress distribution obtained from press forming analysis as feedback input for the springback analysis. This feedback mechanism allows the simulation to account for the actual stress state in high-strength materials, enabling accurate prediction of springback-induced dimensional changes while maintaining the use of high-strength metal sheets.
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 allows for accurate prediction of shape changes over time, improving dimensional accuracy and manufacturing efficiency in automotive parts by simulating stress relaxation and its effect on the shape of press formed parts.
Implementation Method 1
a phenomenon in which a structural member that keeps receiving a high press load from the outside gradually deforms, such as a creep phenomenon
Data Source
AI summary
A shape change prediction method for a press formed part predicts a shape change of the press formed part over time after springback at a moment of a release from a press-forming die, and includes: a shape/residual stress immediately after the springback acquisition step of acquiring a shape and a residual stress of the press formed part immediately after the springback by a springback analysis of the press formed part; a residual stress relaxation/reduction setting step of setting a value of a residual stress relaxed and reduced from the acquired residual stress to all bent portions or a part of the bent portions in the press formed part immediately after the springback; and a shape analysis step of determining a shape in which moments of force are balanced for the press formed part in which the value of the residual stress relaxed and reduced in the bent portions is set.