Sheet Metal Preforming and Calibration for Springback Control
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Solution Overview
Problem
Existing methods for manufacturing sheet metal components face challenges in achieving dimensional accuracy due to springback and torsion, particularly with high-strength materials, leading to unwanted deviations in the final component geometry.
Innovation Solution
A two-stage process involving preforming and calibration, where the preforming tool's working surfaces are designed to create a sheet metal preform with controlled deviations from the target geometry, using torsional and frame angle differences with the calibration tool to minimize springback and torsion, ensuring the preform closely matches the final component geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deep drawing with an active external blank holder is used, then material stretching control is improved, but tensile forces in the frame increase causing excessive springback and torsion
Solution Approach 1:
The invention removes the external blank holder from the preforming process, extracting the source of tensile forces that cause springback and torsion. This allows material to flow more freely during forming while still achieving controlled deformation through the preform tool geometry alone.
Solution Approach 2:
Instead of using tensile forces from an external blank holder to control material flow, the invention inverts the approach by using compressive forces and geometric constraints in the preform tool to achieve similar control without the harmful tensile stress state.
2Device complexity
If preform tool working surfaces are designed to match calibration tool working surfaces, then tool simplicity is improved, but springback compensation is insufficient leading to dimensional deviations
Solution Approach 1:
The preform tool is designed with working surfaces that pre-compensate for expected springback and torsion by creating a deliberately distorted preform geometry. This preliminary distortion is calculated to counteract the anticipated elastic recovery, so that after springback, the component achieves the target geometry without requiring complex calibration tool adjustments.
Solution Approach 2:
The invention changes the geometric parameters of the preform tool working surfaces relative to the calibration tool, introducing deliberate deviations in frame angles and torsional orientation. These parameter changes are optimized to compensate for material springback behavior, transforming the tool design from a simple match to a compensated variant.
3Force
If crash forming or embossing/folding without external blank holder is used, then tensile forces are reduced, but preform springback becomes excessive making calibration difficult
Solution Approach 1:
The preform tool applies localized geometric constraints and forming actions at specific areas of the sheet metal, creating controlled deformation zones. By varying the local quality of forming pressure and constraint through the tool geometry, the invention achieves adequate material flow control without requiring tensile forces from an external blank holder.
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 the production of sheet metal components with minimal deviations from the target geometry, eliminating the need for additional calibration processes and improving dimensional accuracy, especially with high-strength materials.
Implementation Method 1
preforming a sheet metal part into a sheet metal preform having in cross-section a bottom, at least one frame, at least one transition between bottom and frame
Implementation Method 2
the excess sheet metal material is compressed substantially in the plane of the sheet metal, and thus, in particular, the sheet thickness increases at least partially
Implementation Method 3
The inhomogeneous stress state of the preform is thereby realigned, thus largely avoiding the undesirable, batch-dependent springback of the component
Implementation Method 4
the undesirable, batch-dependent springback of the component, which occurs particularly with high-strength materials in combination with small sheet thicknesses
Data Source
Figure 1
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AI summary
The invention relates to a method and a device (100) for the production of sheet metal parts (3) that are characterized by substantially reduced spring back.