Metal Bottle Screw Neck Geometry for Sealing and Recapping
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Solution Overview
Problem
Conventional metal bottles with screw parts face issues with sealing performance under high internal pressure, capping machining ease, recapping operability, and dropping impact resistance due to deformation of the first-stage screw thread during post-machining, leading to difficulties in smooth opening and closing of the cap.
Innovation Solution
A method for manufacturing metal bottles where the height of the first-stage screw thread is made equal to the second-stage screw thread before curl formation, and the distance between the apex of each thread and the bottle axis is adjusted to prevent deformation, ensuring the first-stage thread projects equally, enhancing sealing and machining ease while maintaining smooth cap operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the first-stage screw thread height is formed lower than other stages to avoid deformation during curl formation, then smooth opening and closing of the cap is maintained, but sealing performance under high internal pressure deteriorates
Solution Approach 1:
The invention forms the first-stage screw thread with a larger radius of curvature at its apex during the screw molding process, before the curl formation step. This preliminary geometric configuration prevents excessive deformation during subsequent curl formation, allowing the thread to maintain adequate height for sealing while still permitting smooth cap operation. The pre-configured geometry anticipates and compensates for the deformation that will occur during post-machining.
2Manufacturing precision
If the first-stage screw thread apex is positioned closer to the bottle axis, then deformation during curl formation is reduced, but capping machining ease deteriorates
Solution Approach 1:
The invention changes the geometric parameters of the first-stage screw thread by forming its apex with a larger radius of curvature compared to other screw threads. This parameter modification allows the thread to better withstand deformation during curl formation while maintaining sufficient engagement characteristics for capping machining. The altered geometry balances the competing requirements of deformation control and machining ease.
3Reliability
If the first-stage screw thread height is increased to improve sealing performance, then sealing under high internal pressure is improved, but deformation during post-machining increases causing poor operability
Solution Approach 1:
The invention applies preliminary action by configuring the first-stage screw thread with a larger apex radius of curvature during the initial screw molding process. This pre-configuration ensures that when curl formation and other post-machining operations are subsequently performed, the thread experiences controlled deformation that maintains adequate height for sealing while preserving smooth operability for recapping. The preliminary geometric setup prevents the thread from deforming excessively during later processing steps.
Data Source
AI summary
A method for manufacturing a metal bottle having a mouthpiece in an upper part of a bottomed cylindrical bottle body, including forming a screw part on the mouthpiece and then forming a curl at a tip of the mouthpiece. During formation of the screw part, a height of the first-stage screw thread from a tip side in a complete screw part and a height of the second-stage screw thread from the tip side are substantially equal and a distance between an apex part of the first-stage screw thread and a bottle axis is smaller than a distance between the apex part of the second-stage screw thread and the bottle axis. After formation of the curl, a distance between the apex part of the first-stage screw thread and the bottle axis and a distance between the apex part of the second-stage screw thread and the bottle axis are substantially equal.