Threaded Closure with Offset Segments for Deformation Control
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Solution Overview
Problem
Lightweight closures for carbonated soft drinks often deform when screwed onto container necks, leading to uneven vertical displacements and increased leak risk due to stress concentration in the helical thread segments and outer seal, resulting in a 'cocked' closure.
Innovation Solution
The closure features thread segments with varying axial thickness, where some segments have increased thickness towards the top plate, offsetting the contact surface and reducing deformation, and additional material is strategically added to specific segments to compensate for displacement, with features like surface projections or vent channels to enhance sealing and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If material is removed to lightweight the closure, then weight is reduced, but deformation increases causing cocking and leakage
Solution Approach 1:
The patent applies local quality by varying the axial thickness of individual thread segments rather than uniformly thickening the entire closure. Specifically, selected segments have increased thickness while others maintain original dimensions, providing localized reinforcement where stress concentration occurs during screwing operations. This resolves the contradiction by adding material only where needed to prevent deformation and leakage, rather than increasing overall closure weight.
2Strength
If material is added to increase strength, then deformation resistance improves, but weight increases defeating lightweighting
Solution Approach 1:
The patent applies segmentation by dividing the thread formation into multiple discrete segments with independently controlled thicknesses. This allows the closure to be lightweight overall while having strategically thickened segments that provide reinforcement at critical stress points. The segmented approach enables precise material placement to improve deformation resistance without adding unnecessary weight to non-critical areas.
Solution Approach 2:
The patent applies local quality by varying the axial thickness of individual thread segments rather than uniformly thickening the entire closure. Specifically, selected segments have increased thickness while others maintain original dimensions, providing localized reinforcement where stress concentration occurs during screwing operations. This resolves the contradiction by adding material only where needed to prevent deformation and leakage, rather than increasing overall closure weight.
3Ease of manufacture
If uniform thread segments are used, then manufacturing is simple, but uneven stress distribution causes cocking
Solution Approach 1:
The patent applies asymmetry by creating thread segments with non-uniform axial thicknesses distributed around the circumference. This asymmetric configuration compensates for the cocking tendency by providing differential support at different angular positions. The asymmetric design maintains manufacturability through mold-based formation while achieving stable closure alignment during screwing operations.
Solution Approach 2:
The patent applies local quality by varying the axial thickness of individual thread segments rather than uniformly thickening the entire closure. Specifically, selected segments have increased thickness while others maintain original dimensions, providing localized reinforcement where stress concentration occurs during screwing operations. This resolves the contradiction by adding material only where needed to prevent deformation and leakage, rather than increasing overall closure weight.
Data Source
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AI summary
A closure is provided and comprises a top plate and a sidewall depending therefrom. The interior of the sidewall has a screw thread formation comprising a plurality of thread segments. The thread segments collectively define an engagement surface for engagement with an external thread formation on an associated container. A notional helical top surface with a constant pitch extends along the formation, and at least some, but not all, of the segments include material offset from the notional helical top surface towards the top plate.