Headrest Stay End Forming with Thin-Walled R Chamfers
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Solution Overview
Problem
Existing methods for manufacturing headrest stays, such as spinning and swaging processes, often result in cracks due to high tightening forces and inadequate R chamfered shapes that do not meet European automobile standards for passenger safety.
Innovation Solution
A method involving a boring process to create thin-walled portions on metal round pipes, followed by press molding to form R chamfered shapes with a radius of 5 mm or more, which reduces the likelihood of cracks and enhances the structural integrity of the headrest stay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If spinning process or swaging process is used to form R chamfered shape on headrest stay terminal portion, then the terminal portion can be formed with curved shape, but cracks may occur due to high tightening force and inadequate R radius
Solution Approach 1:
The patent applies preliminary action by performing the boring process to create thin-walled portions at the terminal end before performing the press molding process to form the R chamfered shape. This preparatory removal of material reduces the section modulus at the terminal end, allowing the subsequent pressing to form a larger R radius (5mm or more) without requiring excessive tightening force that would cause cracks. The preliminary thinning action enables the final shaping to achieve both the required curved geometry and crack resistance.
2Shape
If high tightening force is applied during spinning or swaging process, then the metal round pipe can be deformed into curved shape, but cracks may occur in the headrest stay
Solution Approach 1:
The patent applies local quality by creating thin-walled portions at specific locations (terminal ends) of the metal round pipe through the boring process, rather than uniformly thinning the entire pipe. This localized material removal concentrates the plastic deformation during press molding to specific regions where the R chamfered shape is formed, allowing adequate R radius with controlled tightening force. The local thinning enables targeted shaping without compromising the overall structural integrity of the headrest stay.
3Ease of manufacture
If R radius is made small to facilitate shaping, then the manufacturing process becomes easier, but cracks may occur and safety standards may not be met
Solution Approach 1:
The patent applies parameter changes by modifying the wall thickness parameter at the terminal end through the boring process, creating thin-walled portions with reduced thickness before press molding. This parameter change enables the subsequent forming process to achieve a larger R radius (5mm or more) required by safety standards. The preliminary thinning reduces the material volume that needs to be deformed, making it easier to form the required curved shape with adequate R radius without excessive tightening force that would cause cracks.
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 effectively prevents cracks and maintains the rigidity of the thin-walled portions, ensuring a smooth and secure R chamfered shape that meets safety standards without significant external shape changes or buckling distortions.
Implementation Method 1
performing a boring process on the metal round pipe by a cutting length of 5 mm or more from each of both distal ends of the metal round pipe to form a thin-walled portion
Implementation Method 2
pressing the distal ends of the metal round pipe against a bottom surface of the cylindrical hole to form each of the distal ends into an curved chamfered shape
Implementation Method 3
bending the metal round pipe to have a shape of the headrest stay
Data Source
AI summary
A headrest stay is manufactured with a metal round pipe having a predetermined length and a predetermined thickness by performing a boring process on the metal round pipe by a cutting length of 5 mm or more from each of both distal ends of the metal round pipe to form a thin-walled portion that is thinner than the predetermined thickness; forming each of the distal ends of the metal round pipe into an curved chamfered shape having a radius of 5 mm or more by inserting each of the distal ends of the metal round pipe into a cylindrical hole; and bending the metal round pipe to have a shape of the headrest stay.