Structural Member Press Forming With Split Lower Die Crack Control
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Solution Overview
Problem
Structural members with a flange and member body connected via a corner portion are prone to cracks during press working, especially when the curvature radius is small or when high-strength metal sheets are used.
Innovation Solution
A method involving a press tooling with a lower die comprising separate first and second lower dies, where the second die is initially retreated and later aligned to facilitate material flow, reducing distortion and crack formation in the continuous flange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If press working is performed on a metal sheet to form a structural member with a corner portion connecting the member body and flange, then the structural member can be produced efficiently, but cracks are generated in the continuous flange especially when the curvature radius of the corner portion is small or when high-strength metal sheets are used
Solution Approach 1:
The lower die is divided into a first lower die and a second lower die that are separate bodies. The first lower die forms the member body while the second lower die forms the flange. This segmentation allows independent optimization of forming conditions for each part, enabling the flange to be formed after the member body, which reduces restraint on material flow and suppresses crack generation in the continuous flange during press working
2Device complexity
If a single lower die is used to form both the member body and flange simultaneously, then the device complexity is reduced, but the material flow is restrained causing cracks in the continuous flange
Solution Approach 1:
The lower die is segmented into two separate bodies (first lower die and second lower die) that can move independently. This allows the second lower die to be positioned retreated relative to the first lower die during forming, providing adequate space for material flow from the member body to the flange without restraint, thereby preventing cracks while maintaining reasonable device complexity through the use of a cam mechanism for coordination
Solution Approach 2:
The second lower die is designed to be movable relative to the first lower die through a cam mechanism. During the forming process, the second lower die moves from a retreated position to an aligned position, dynamically adapting to the material flow requirements. This dynamic adjustment allows the die structure to accommodate the forming sequence without excessive complexity
3Reliability
If the second lower die is positioned retreated relative to the first lower die during forming, then material flow is facilitated and cracks are suppressed, but the device complexity increases due to additional mechanisms required
Solution Approach 1:
A cam mechanism is employed to automatically coordinate the movement of the second lower die relative to the first lower die. The cam mechanism converts the vertical pressing motion into the required horizontal movement sequence, where the second lower die moves from a retreated position to an aligned position during forming. This automated coordination reduces the need for complex manual or controlled adjustments while achieving the desired material flow conditions
Solution Approach 2:
The cam mechanism acts as an intermediary device that mediates between the pressing action and the position adjustment of the second lower die. It automatically provides the necessary movement sequence without requiring complex control systems or manual intervention, thereby suppressing cracks while limiting the increase in device complexity to a relatively simple mechanical linkage
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 method effectively suppresses crack generation in the continuous flange, improves yield by omitting trimming steps, reduces material input, and decreases greenhouse gas emissions.
Implementation Method 1
a forming step of performing forming by subjecting the starting material to cold press working by using a press tooling
Implementation Method 2
the pad and the upper die are relatively brought closer to the lower die in the pressing direction, and the starting material is sandwiched between the pad and the first lower die to be held
Data Source
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AI summary
A method for producing a structural member (10) includes a preparing step of a starting material (M), and a forming step of subjecting the starting material (M) to cold press working by using a press tooling (20). The press tooling (20) includes a pad (23), an upper die (22), and a lower die (21). The lower die (21) includes first and second lower dies (211, 212). The forming step includes first and second steps. In the first step, in a state where a side surface (212c) of the second lower die (212) is retreated with respect to a side surface (211c) of the first lower die (211) as viewed from a pressing direction, the starting material (M) is held by the pad (23) and the first lower die (211). In the second step, the starting material (M) is sandwiched between the upper die (22) and the first lower die (211), and the second lower die (212) is moved so that the side surface (212c) is aligned with the side surface (211c), so as to sandwich the starting material (M) between the upper die (22) and the second lower die (212).