Segmented Crash Box Welding for Thin Sheet Impact Absorption
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Solution Overview
Problem
The existing crash boxes with reduced sheet thickness face challenges in maintaining impact energy absorption performance and stable buckling due to difficulties in welding and deformation, particularly when using high-strength steel sheets.
Innovation Solution
A crash box design featuring a tubular body with outward flanges and a set plate, where the tubular body is press molded with groove portions and outward flanges, allowing for effective welding and impact energy absorption, even with sheet thicknesses less than 1.4 mm, using spot, fillet arc, or laser welding, and incorporating locking sections on the set plate to prevent collapse during impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the sheet thickness of the tubular body is reduced to reduce vehicle weight, then weight is reduced, but the end portion is burned through by heat input in butt arc welding with a set plate, raising the risk of declining the strength of a weld zone
Solution Approach 1:
The invention divides the tubular body into two separate tubular bodies that are joined together. By segmenting the structure, the patent enables the use of thinner sheets (1.2-1.4mm or smaller) while maintaining weldability through alternative joining methods such as spot welding or self-piercing riveting, avoiding the burn-through issue associated with butt arc welding of thin sheets. This segmentation allows weight reduction while preserving structural integrity and weld zone strength.
Solution Approach 2:
The invention introduces an intermediary joining method between the tubular body and set plate, replacing direct butt arc welding with spot welding or self-piercing riveting. These intermediary joining methods act as mediators that can properly join thin-sheet tubular bodies without causing burn-through, thereby maintaining both weight reduction and weld zone strength.
2Weight of moving object
If the sheet thickness of the tubular body is reduced, then weight is reduced, but impact energy absorbing performance and stable buckling are compromised
Solution Approach 1:
By dividing the tubular body into two segments joined together, the invention creates a structure that can achieve stable buckling behavior even with thin sheets (1.2-1.4mm or smaller). The segmented structure allows for controlled deformation patterns that maintain impact energy absorbing performance while reducing overall weight.
Solution Approach 2:
The invention changes key parameters including sheet thickness (reducing to 1.2-1.4mm or smaller), joining method (spot welding or self-piercing riveting), and structural configuration (two joined tubular bodies). These parameter changes collectively enable weight reduction while maintaining or improving impact energy absorption reliability through optimized deformation characteristics.
3Strength
If high-strength steel sheets are used for the tubular body, then strength is improved, but molding the folded portion becomes difficult
Solution Approach 1:
The invention eliminates the need for folded portions by segmenting the tubular body into two separate pieces that are joined together. This approach avoids the molding difficulties associated with high-strength steel sheets while maintaining or improving strength through the segmented configuration and appropriate joining methods.
Solution Approach 2:
Instead of forming a folded portion in a single tubular body (the conventional approach that becomes difficult with high-strength sheets), the invention inverts the approach by using two separate tubular bodies joined together. This inversion eliminates the complex folding operation while achieving the desired structural characteristics with high-strength materials.
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 design prevents burn-through during welding, enhances impact energy absorption, and maintains stable repetitive buckling, even with thinner sheets, while ensuring a lightweight and robust crash box structure.
Implementation Method 1
the tubular body buckles and is plastically deformed into a bellows when loaded with impact load in the axis direction of the tubular body, so as to absorb impact energy
Implementation Method 2
the set plate (an attachment plate) that is welded to this tubular body at one end portion in the longitudinal direction of the tubular body by butt arc welding or the like
Data Source
AI summary
A crash box has excellent axial crushing performance and in which, even if the sheet thickness of a tubular body constituting the crash box is smaller than 1.4 mm, good welding can be performed with the tubular body butted against a set plate. The crash box (1) having a metallic longer-length tubular body and a method for producing the crash box are provided. The tubular body has a basic cross-sectional shape that is a flat polygon surrounded by a plurality of ridges (2-1 to 2-4) extending in a longitudinal direction and a plurality of side wall portions (4), includes one or more groove portions (3-1 and 3-2) on side wall portions (4) on long sides substantially parallel to the major axis direction of the cross section that extend in longitudinal direction, and includes outward flanges (5-1 to 5-4) in an end portion in the longitudinal direction.