Hat-Section Press Forming With Die-Gap Compression Against Buckling
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Solution Overview
Problem
Press-forming technologies face challenges in achieving accurate dimensional stability for hat cross-sectional components without flange portions, particularly due to springback deformation and warping issues in components with curved vertical walls, which existing solutions fail to adequately address.
Innovation Solution
A press form device that applies a controlled compression stress to vertical wall portions using a die structure with a punch, pad, and bending blades, where stoppers constrain the material, and cushion components manage pressure to reduce warping, with a compression amount set between 2% and 6% of the vertical wall height, and a clearance between the punch and bending blades set at 90% of the sheet thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compression stress is applied to reduce warping, then dimensional accuracy is improved, but buckling occurs in the vertical wall portions
Solution Approach 1:
The bending blade is divided into an upper die component and a lower die component that face each other with a gap. This segmentation allows the application of compression stress while maintaining structural support to prevent buckling, resolving the contradiction between improving dimensional accuracy and avoiding buckling deformation.
Solution Approach 2:
A cushion component is introduced as an intermediary element between the upper and lower dies. This cushion component controls the compression stress applied to the vertical wall portions, enabling dimensional accuracy improvement while preventing excessive compression that would cause buckling.
2Productivity
If a simple press-forming process is used, then productivity is improved, but springback deformation causes poor dimensional accuracy
Solution Approach 1:
The bending blade components are positioned in advance with a predetermined gap corresponding to the compression amount. This preliminary arrangement enables the press-forming process to automatically apply the correct compression stress during normal operation, improving both productivity and dimensional accuracy without requiring complex real-time control.
3Manufacturing precision
If the gap between upper and lower dies is reduced to apply compression, then warping is reduced, but the risk of buckling increases
Solution Approach 1:
The cushion component serves as a mediator between the upper and lower dies, controlling the compression stress applied when the gap is reduced. This allows warping to be effectively controlled through the narrowed gap while the cushion prevents excessive compression that would cause buckling, maintaining structural stability.
4Device complexity
If conventional die structures are used, then device complexity is low, but they cannot effectively address warping in curved vertical wall portions
Solution Approach 1:
The bending blade is segmented into upper and lower die components with a gap between them. This segmentation provides a straightforward structural modification that enables effective compression stress application to curved vertical wall portions, improving warping control without significantly increasing device complexity.
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
The solution effectively reduces warping and improves dimensional accuracy of press-formed articles with hat cross-sectional shapes, preventing buckling and enhancing the quality of the final product.
Implementation Method 1
a first cushion component which is elastically expandable and contractible in the press direction
Implementation Method 2
a second cushion component interposed between the upper die component and the lower die component, maintaining the interval, and contractible in the press direction at a predetermined pressure or more
Implementation Method 3
springback deformation due to elastic recovery occurs in a press-formed article after form release
Data Source
AI summary
To reduce warping of vertical wall portions without causing buckling during pressing. Press-forming into a hat cross-sectional shape having one linear vertical wall portion and the other curved vertical wall portion and not having a flange portion is performed. A punch and a pad sandwiching a top sheet portion therebetween, bending blades, and stoppers are provided. The punch is supported by a first cushion component. The bending blades each have an upper die component and a lower die component disposed facing each other in the press direction with an interval (D) equal to a set compression amount in the range of 2% or more and 6% or less of the heights of the vertical wall portions and a second cushion component interposed between the upper die component and the lower die component, maintaining the interval (D), and contractible in the press direction. The cushion pressure of the second cushion component is lower than the cushion pressure of the first cushion component and has such cushion pressure that the second cushion component does not contract during the bend-forming of the vertical wall portions. The clearance between the side surface of the punch and the bending blades is 90% or more of the sheet thickness of a material to be processed and less than the sheet thickness.