Metal Bottle Cap Thread Geometry for Sealing and Torque
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Solution Overview
Problem
Conventional metal bottle caps with thread sections having an effective thread number of 1.5 to 1.7 experience issues such as bridge breakage, uneven sealing, and increased torque for opening, due to variations in thread density, leading to poor sealing and handling difficulties.
Innovation Solution
A metal bottle cap design with a thread section having an effective thread number of 2.0 to 2.5, formed with a pitch of eight-thread per inch, and a slant angle between 33° and 55°, ensuring equal thread compression and enhanced sealing, while preventing bridge breakage and reducing opening torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the effective thread number is increased from 1.5-1.7 to 2.0-2.5, then the sealing uniformity and bridge integrity are improved, but the manufacturing complexity increases
Solution Approach 1:
The patent changes the thread geometry parameters by increasing the effective thread number from 1.5-1.7 to 2.0-2.5, adjusting the thread pitch to 8 threads per inch, and modifying the slant angle to 33°-55°. These parameter changes improve sealing uniformity and prevent bridge breakage while maintaining manufacturing feasibility through standardized thread dimensions.
Solution Approach 2:
The patent applies different thread characteristics to different regions of the mouth section. The thread section has optimized local properties with 2.0-2.5 effective threads, while the expanding section below it has a different geometry (larger diameter, no threads). This local differentiation ensures proper sealing at the thread interface while maintaining structural integrity in the expanding section.
2Reliability
If the effective thread number is increased from 1.5-1.7 to 2.0-2.5, then the bridge breakage is prevented, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise thread parameters (8 threads per inch pitch, 33°-55° slant angle, 2.0-2.5 effective thread number) that optimize the distribution of compressive forces during cap engagement. These parameter changes ensure that the bridge section experiences more uniform stress distribution, preventing breakage while providing clear manufacturing targets for precision control.
Solution Approach 2:
The thread section is pre-formed with optimized geometry (2.0-2.5 effective threads) before cap engagement. This preliminary configuration ensures that when the cap is applied, the compressive forces are distributed evenly across multiple thread contacts, preventing bridge breakage during the engagement process without requiring high-precision adjustment during assembly.
3Reliability
If the thread compression is made equal, then the sealing performance is improved, but the device complexity increases
Solution Approach 1:
The patent achieves equal thread compression by optimizing the thread geometry parameters: 2.0-2.5 effective thread number, 8 threads per inch pitch, and 33°-55° slant angle. These parameter changes ensure that each thread contact experiences similar compressive forces during cap engagement, improving sealing uniformity without requiring complex active control mechanisms.
Solution Approach 2:
The patent creates homogeneous compression distribution across all thread contacts through optimized thread geometry. The uniform pitch (8 threads per inch) and consistent slant angle (33°-55°) ensure that each thread engages with similar force, achieving homogeneous sealing pressure across the entire interface without requiring variable or adaptive control systems.
4Ease of operation
If the slant angle is set between 33° and 55°, then the thread engagement is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a slant angle range of 33°-55° for the thread geometry. This parameter change optimizes the engagement characteristics by ensuring proper force distribution and contact between mating threads, improving ease of operation while providing a practical manufacturing tolerance range rather than requiring ultra-precise angle control.
Solution Approach 2:
The slant angle optimization applies specifically to the thread section geometry, creating local quality improvements at the engagement interface. The 33°-55° angle range is tailored for the thread portion while the expanding section below maintains different geometry, ensuring optimal engagement where needed without unnecessarily constraining other manufacturing areas.
Data Source
AI summary
An effective thread number in the thread section which is disposed on the mouth section of the bottle is formed to be 2.2. That is, the thread section is formed such that the thread section 13 should serve effectively in the mouth section such that an interval between a start position and an end position should be 2.0 to 2.5. In the bottle can member 11 which has such a thread section, an outer diameter of the thread section which is formed on the mouth section is 28 to 38 mm. Also, the thickness of the mouth section is 0.25 to 0.4 mm. The thread section which has the effective thread number 2.0 to 2.5 is formed by eight-thread per inch pitch. By doing this, it is possible to put the cap desirably.