Residual Stress Mapping for Press Forming Springback Variation
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Solution Overview
Problem
Existing methods for evaluating springback in press formed parts do not effectively identify the factors contributing to variation in springback amount due to scattering in press forming conditions, including material properties and environmental changes, which hinders shape accuracy and stability in mass production.
Innovation Solution
A method involving residual stress distribution calculations under different press forming conditions, followed by stress replacement analysis to identify specific portions in the press formed part that contribute to springback variation, using finite element analysis to quantify the impact of varying conditions on springback amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional springback evaluation methods are used, then springback amount can be measured, but the factors contributing to variation in springback amount due to scattering in press forming conditions cannot be identified
Solution Approach 1:
The press formed part is divided into multiple evaluation regions, and residual stress distributions are calculated and compared for each region under different press forming conditions. This segmentation allows identification of specific portions contributing to springback variation rather than treating the entire part as a single unit.
Solution Approach 2:
The method calculates residual stress distributions under multiple sets of press forming conditions that include scattering in material properties and environmental factors. By changing parameters such as material strength, thickness, temperature, and friction coefficient, the method identifies which regions show significant stress changes that correlate with springback variation.
2Productivity
If press forming conditions are scattered in mass production, then production flexibility is maintained, but shape accuracy and stability of press formed parts deteriorate
Solution Approach 1:
The method performs preliminary calculations of residual stress distributions under various press forming conditions before actual production. By identifying evaluation regions and their sensitivity to condition variations in advance, the method enables proactive compensation strategies to be developed, allowing mass production to proceed while maintaining shape accuracy through targeted countermeasures.
3Measurement precision
If residual stress distribution is calculated under multiple press forming conditions, then variation factors can be identified, but calculation time and computational complexity increase
Solution Approach 1:
The method focuses calculations on specific evaluation regions that are most sensitive to press forming condition variations, rather than analyzing the entire press formed part uniformly. By concentrating computational resources on critical regions where residual stress changes significantly, the method achieves accurate variation factor identification with reduced calculation time compared to full-part analysis.
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
Accurately identifies the portions responsible for springback variation, enabling targeted countermeasures to improve shape stability and reduce springback in press formed parts during mass production.
Implementation Method 1
Springback is the behavior of elastic recovery, which is generated when internal residual stress (bottom dead center residual stress) in a press formed part at the time (bottom dead center) of completion of sandwiching by upper and lower tools of press forming is released at the time of die release.
Data Source
AI summary
A method for identifying a variation factor portion of a springback amount, including: performing press forming analysis under first press forming conditions, and calculating a residual stress distribution in a press formed part; performing springback analysis on the press formed part, and calculating a first springback amount; performing press forming analysis under second press forming conditions, and calculating a residual stress distribution in the press formed part; replacing a value of residual stress in a partial area of the residual stress distribution; performing springback analysis on the press formed part for which the value of the residual stress has been replaced, and calculating a second springback amount; obtaining a difference between the second springback amount and the first springback amount; and identifying a portion in the press formed part that is a factor for variation in springback amount of the press formed part based on the obtained difference.