Double-Sided Engaging Element With Missing Portions
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Solution Overview
Problem
Conventional metallic double-sided engaging elements for slide fasteners lack flexibility in bending and twisting around the coupling axis line, leading to reduced operational ease and potential stress concentration on forming dies, which affects their service life.
Innovation Solution
A double-sided engaging element design featuring a thin sheet coupling head with a central elevated portion and projecting portions, where the dimension between inside elevation startup edges of the projecting portions is set smaller than that of the central elevated portion, and the outside corner of the projecting portions includes a first missing portion to enhance flexibility and reduce stress concentration during forming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the double-sided engaging element uses a conventional design with projecting portions having full outer corners, then the coupling strength and structural integrity are improved, but the flexibility for bending and twisting around the coupling axis line deteriorates
Solution Approach 1:
The patent removes material from the outer corners of the projecting portions by creating missing portions. This extraction of material reduces stress concentration points and allows the engaging element to bend and twist more easily around the coupling axis line, directly resolving the contradiction between structural integrity and operational flexibility.
Solution Approach 2:
The patent modifies the geometric parameters of the projecting portions by creating missing portions at the outer corners. This changes the local stiffness and stress distribution characteristics, enabling the element to achieve both adequate coupling strength and improved flexibility for bending and twisting operations.
2Stability of the object's composition
If the double-sided engaging element uses a conventional design without missing portions, then the structural completeness is improved, but the stress concentration on forming dies during manufacturing increases, reducing die service life
Solution Approach 1:
The patent extracts material from the outer corners of the projecting portions to create missing portions. This removes stress concentration points that would otherwise occur during forming operations, significantly reducing the stress load on forming dies and extending their service life while maintaining adequate structural completeness for functional requirements.
Solution Approach 2:
The patent converts what would normally be harmful stress concentration points at the outer corners into beneficial missing portions. This transformation eliminates the harmful stress concentration effect during manufacturing, protecting the forming dies from excessive wear and extending their operational life.
3Ease of manufacture
If the dimension between inside elevation startup edges of projecting portions is set equal to that of central elevated portion, then the manufacturing simplicity is improved, but the flexibility for bending and twisting deteriorates
Solution Approach 1:
The patent applies different dimensional characteristics to different parts of the engaging element. The missing portions are specifically created at the outer corners of the projecting portions, creating local variations in geometry that enhance flexibility where needed while maintaining adequate dimensional relationships elsewhere for proper coupling function.
Solution Approach 2:
The patent changes the dimensional parameters of the projecting portions by introducing missing portions at the outer corners. This modifies the local geometric parameters to reduce stiffness and improve flexibility for bending and twisting, while the overall dimensional relationships between major features remain suitable for manufacturing.
Data Source
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AI summary
A double-sided engaging element (12,112) for a slide fastener (10), comprising a central elevated portion (74) elevated from a coupling base surface (70); and a pair of right and left projecting portions (72,172) formed to project from a body portion (78) toward the central elevated portion (74) and to be elevated from the coupling base surface (70), wherein a central elevated portion (74) of a mating element is detachably coupled in a dent surrounded by the central elevated portion (74), the right and left projecting portions (72,172) and a stepped surface (82). A dimension (T0) between inside elevation startup edges of the right and left projecting portions (72,172) is set smaller than a dimension (R0) between right and left elevation startup edges of the central elevated portion (74), and a first missing portion (88,188) is formed on an outside corner of an end portion of each of the right and left projecting portions (72,172) opposing the central elevated portion (74).