Bottle Cap Weakened Line Tear Propagation
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Solution Overview
Problem
Existing caps for large liquid containers, such as water bottles, are difficult to remove and reattach due to strong interference between the neck and internal reliefs, making extraction challenging, especially when the skirt is torn around the neck.
Innovation Solution
The cap design includes a weakened line that extends in a rectilinear fashion along and below the bulge line, then inclined upwards, and finally along and above it, guiding the tear to reduce the fixing effect and facilitate cap removal by neutralizing the bulge line's participation in the cap's retention around the neck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the skirt is provided with internal reliefs to wedge on the neck for holding the cap, then the cap is securely retained around the neck, but the extraction of the cap becomes difficult and sometimes almost impossible due to strong interference between the neck and internal reliefs
Solution Approach 1:
The weakened line is divided into multiple segments: a first part extending axially below the bulge line, a second part inclined at an angle between 30° and 60° passing through the bulge line, and a third part extending axially above the bulge line. This segmentation allows the tear to propagate in a controlled manner that neutralizes the fixing effect of the bulge line while maintaining cap retention during normal use
Solution Approach 2:
The inclined second part of the weakened line acts as an intermediary that transitions the tear from the bottom side to the top side of the bulge line. This inclined segment passes through the bulge line at an angle, effectively neutralizing its fixing effect and facilitating cap extraction while the first and third parts maintain structural integrity during normal operation
2Device complexity
If a stop for the tear is arranged projecting inside the skirt to prevent tearing beyond what is necessary, then the tearing is controlled, but the cap extraction still requires handling in two stages which is restrictive and difficult
Solution Approach 1:
The weakened line is designed with dynamic geometry - the second part is inclined at an angle between 30° and 60° relative to the axial direction, allowing the tear to propagate dynamically through the bulge line. This dynamic design enables the tear to neutralize the fixing effect of the bulge line, making cap extraction easier while maintaining controlled tearing
3Device complexity
If the weakened line includes only a main rectilinear part extending axially below the free end, then the structure is simple, but the user must manually propagate the tear all around the neck which is difficult and restrictive
Solution Approach 1:
The weakened line is pre-configured with three distinct parts including an inclined second part that passes through the bulge line at an angle between 30° and 60°. This preliminary configuration enables the tear to automatically propagate through the bulge line and neutralize its fixing effect, eliminating the need for manual tear propagation around the entire neck
Data Source
AI summary
A cap for closing a neck of a bottle is disclosed. The cap includes a lid for closing off the neck and a skirt for fixing to the neck. The skirt is provided with a bulge line for interfering by wedging with the neck, a weakened line to be ruptured by propagation of a tear, and a stop means for preventing the tearing propagating in the rectilinear extension of a first part of the weakened line that runs along the bulge line while being situated on the side of the latter opposite to the lid. The weakened line also includes second and third substantially rectilinear parts which, on the periphery of a skirt, follow on respectively from the first part to the second part of the weakened line. The second part of the weakened line avoids the stop means and extends on either side of the bulge line, while being inclined both with respect to the bulge line and with respect to the direction of the axis of the skirt. The third part of the weakened line extends along the bulge line while being situated on the side of the bulge line turned towards the lid.