Forming Tool Surface Compensation for Sheet Metal Springback
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Solution Overview
Problem
Existing methods for correcting springback in sheet metal forming processes, such as global scaling approaches, result in rough approximations of workpiece stress states, leading to undesirable local deformations, pressure marks, and dimensional deviations, which can impair subsequent springback compensation and require time-consuming rework.
Innovation Solution
A method that simulates elastic-plastic forming operations using finite element methods to determine locally adapted scaling based on locally prevailing stresses, adjusting stress components, and generating a scaled working surface geometry that accounts for local shrinkage and distortions to improve springback compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If global scaling approaches are used to correct springback, then tool correction can be performed, but rough approximations of workpiece stress states result, leading to local deformations, pressure marks, and dimensional deviations
Solution Approach 1:
The patent divides the workpiece into multiple finite elements and calculates stress states independently for each element. This segmentation allows local stress variations to be captured accurately, replacing the global scaling approach with a localized element-by-element analysis that determines precise scaling factors for each region based on its specific stress state.
Solution Approach 2:
The patent applies different scaling factors to different regions of the workpiece based on locally calculated stress states. Each finite element receives a customized scaling factor derived from its specific stress components, enabling localized correction of springback effects rather than applying a uniform global scaling factor, thereby avoiding local deformations and pressure marks.
2Manufacturing precision
If global scaling approaches are used, then tool correction is achieved, but undesirable local deformations and pressure marks occur
Solution Approach 1:
By segmenting the workpiece into finite elements and analyzing stress states locally, the patent identifies specific regions prone to local deformations and pressure marks. This enables targeted correction strategies applied to individual elements, preventing the propagation of harmful local effects while maintaining overall shape accuracy.
Solution Approach 2:
The patent applies localized quality control by calculating and applying specific scaling factors to each finite element based on its stress state. This local customization prevents uniform scaling-induced defects like pressure marks while maintaining global dimensional accuracy, as each region is corrected according to its specific mechanical behavior.
3Manufacturing precision
If conventional tool correction methods are used, then springback compensation is attempted, but convergence behavior in tool setup deteriorates and time-consuming rework is required
Solution Approach 1:
The patent performs preliminary finite element analysis and stress state calculation during the tool design phase, before actual tooling and production begin. By pre-calculating scaling factors for each finite element based on simulated stress states, the method enables direct application of corrected tool geometry without iterative adjustments, significantly reducing tool setup time and improving convergence behavior.
Solution Approach 2:
The patent replaces traditional iterative mechanical trial-and-error tool correction methods with a computer-based finite element analysis system. This substitution allows rapid calculation of precise scaling factors and corrected tool geometries, eliminating time-consuming physical rework and improving convergence toward the final tool design.
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 reduces local deformations and pressure marks, enhances the quality of springback compensation, and improves convergence behavior in tool setup, ensuring accurate production of complex formed parts with minimal rework.
Implementation Method 1
a) Simulating an elastic-plastic forming operation using a discretization method, in particular using a finite element method
Implementation Method 2
d) Simulating an elastic deformation of the workpiece starting from the first configuration and based on the local stresses
Implementation Method 3
c) Adjusting the determined local stresses in terms of sign and/or magnitude
Data Source
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AI summary
The invention relates to a method for determining a springback-scaled effective surface of a forming tool for producing a complex formed part by drawing, to a method for producing a forming tool, to a method for producing a complex formed part, and to a computer program product. Use in computer-aided, simulation-based production planning.