Tailored Blank Weld Line Orientation in Stretch Flange Deformation
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Solution Overview
Problem
The existing techniques for producing press-formed products using tailored blanks (TWB) face limitations in design flexibility due to the need to avoid weld lines in stretch flange deformation fields, leading to potential cracking and increased production steps, which hinders weight reduction and functional enhancement.
Innovation Solution
A press-formed product design where the weld line intersects with the inner and outer peripheral edges of an arc-shaped area, with a specific angle of 17 to 84° relative to the maximum principal strain direction, and a relative strain difference of no more than 0.030 between the weld line and the metal sheet, allowing for improved placement and reduced cracking during press-working.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the weld line is placed in the stretch flange deformation field, then the design freedom is improved, but cracking occurs between the weld line and base metal sheet
Solution Approach 1:
The patent changes the geometric parameter of the weld line orientation by specifying a particular angle range (17° to 84°) relative to the maximum principal strain direction. This parameter change allows the weld line to withstand the deformation stresses in the stretch flange field without cracking, thereby enabling placement within the deformation field while maintaining reliability.
2Reliability
If the weld line is placed outside the stretch flange deformation field, then cracking is avoided, but the design freedom is reduced and production steps increase
Solution Approach 1:
Instead of avoiding the stretch flange deformation field entirely, the patent changes the orientation parameter of the weld line to a specific angle range (17° to 84°) relative to the maximum principal strain direction. This allows the weld line to be placed within the deformation field while maintaining cracking resistance, thereby increasing design freedom without sacrificing reliability.
3Manufacturing precision
If additional production steps (trimming, restriking) are applied, then the formability is improved, but the productivity is reduced
Solution Approach 1:
The patent performs preliminary action by pre-determining the optimal weld line orientation angle (17° to 84° relative to maximum principal strain direction) during the design stage. This preliminary configuration of the weld line ensures that the product can be formed directly in one press-working operation without requiring additional trimming or restriking steps, thereby maintaining high productivity while achieving good formability.
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 enhances the design freedom for press-formed products by reducing cracking and production steps, enabling better weight reduction and functional enhancement while maintaining anti-collision performance.
Implementation Method 1
a portion of the blank (metal sheet) may undergo stretch flange deformation depending on the shape of the press-formed product. The stretch flange deformation refers to a deformation form in which as a working tool (press tooling) intrudes and moves into a blank, the blank stretches in a direction along the moving direction of the working tool as the working tool (press tooling) moves into the blank, and at the same time it stretches in a circumferential direction perpendicular to the moving direction.
Implementation Method 2
An angle formed by the weld line and a maximum principal strain direction is 17 to 84°. In a case where a press-formed product is shaped by press-working, an arc-shaped area on an inner side of curve of a curved region becomes a stretch flange deformation field, a weld line of the tailored blank intersects with an inner peripheral edge and an outer peripheral edge of the arc-shaped area, and an angle formed by the weld line and a maximum principal strain direction is 17 to 84°.
Data Source
AI summary
A press-formed product is shaped by press-working from a tailored blank made up of a plurality of metal sheets butt-welded together. The press-formed product includes a flange section, and an arc-shaped area which is an area of the flange section which is formed by stretch flange deformation, and in which an inner peripheral edge is open. A weld line of the tailored blank intersects with the inner peripheral edge and an outer peripheral edge of the arc-shaped area. An angle θ formed by the weld line and a maximum principal strain direction of the stretch flange deformation is 17 to 84°.