Inward Continuous Flange Forming to Suppress Press-Molding Wrinkles
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Solution Overview
Problem
Existing techniques fail to effectively suppress wrinkles in the flange portion of press-molded products, particularly those made from high-tensile steel with a tensile strength of 340 MPa or more, without forming notches, which affects the bonding strength and rigidity of vehicle body reinforcing members.
Innovation Solution
A press-molded product with an inward continuous flange is formed using a steel plate with a tensile strength of 340 MPa or more, featuring a ridge portion and surface portions with a specific plate thickness distribution and flange width, where the ridge-portion flange has equal or greater plate thickness on both sides of the center area, and the flange width satisfies the condition 0.2 × rf ≤ Lf ≤ rf, where rf is the curvature radius and Lf is the flange width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inward flange is formed by shrinking the ridge-portion flange, then the flange can be bonded to other members, but wrinkles are generated in the ridge-portion flange causing bonding gaps and assembling problems
Solution Approach 1:
The patent applies preliminary action by forming drawing beads on the inner surface of the mold cavity before the actual flange forming process. These pre-formed drawing beads create controlled stress concentration points that guide the plastic deformation during shrinking, preventing uncontrolled wrinkle formation while enabling complete inward flange formation without notches
Solution Approach 2:
The patent changes the geometric parameters of the mold cavity by forming drawing beads with specific dimensions (depth of 0.5-2.0mm and length of 50-200mm) on the inner surface. This parameter modification alters the stress distribution during flange shrinking, enabling controlled deformation that eliminates wrinkles while maintaining bonding surface quality
2Manufacturing precision
If a notch is formed in the ridge-portion flange to suppress wrinkles, then wrinkle generation is prevented, but the continuous flange structure is broken and bonding performance is degraded
Solution Approach 1:
Instead of forming notches that break the flange continuity, the patent uses preliminary action by pre-forming drawing beads on the mold inner surface. This approach suppresses wrinkles through controlled stress distribution while maintaining the continuous structure of the inward flange, ensuring both wrinkle suppression and bonding performance
3Manufacturing precision
If the flange width and curvature radius are optimized, then wrinkle generation is suppressed, but the bonding area is reduced
Solution Approach 1:
The patent optimizes the parameters by forming drawing beads with specific depth (0.5-2.0mm) and length (50-200mm) on the mold inner surface, and by controlling the flange width to be 0.1-0.3 times the curvature radius. These parameter changes enable wrinkle suppression through controlled stress distribution while maintaining adequate bonding area for reliable connections
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 prevents the generation of wrinkles and enhances the bonding strength and rigidity of the press-molded product when used as a vehicle body reinforcing member, allowing for improved load transfer efficiency without notches in the flange.
Implementation Method 1
a bending step of relatively moving the bending tool in a direction toward the inner area so as to form the flange
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(A)~3(D)
AI summary
[Object] To provide a press-molded product including an inward continuous flange and capable of improving performance involved with the bonding strength between a reinforcing member and the other member or the rigidity of a vehicle body without forming a notch in a ridge-portion flange so as to prevent a defect generated during a press-molding process. [Solution] Provided is a press-molded product of a metal plate which is formed by a steel plate having a tensile strength of 340 MPa or more and includes a ridge portion extending in a predetermined direction and first and second surface portions respectively extending from both ends of a ridge line formed by the ridge portion, the press-molded product including: an inward continuous flange which is obtained by continuously forming a ridge-portion flange formed inward in an end portion of the ridge portion, a first flange formed inward in at least a part of an area of an end portion of the first surface portion, and a second flange formed inward in at least a part of an area of an end portion of the second surface portion. Regarding a plate thickness of an edge portion of the ridge-portion flange, the ridge-portion flange has a plate thickness distribution in which a plate thickness of a portion of each of areas on both sides of a circumferential center area is equal to or larger than a plate thickness of the center area.