Drum Hoop Bolt Insertion Inversion for Aesthetic and Strength
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Solution Overview
Problem
Existing percussion instruments face issues with the cosmetic appearance of the striking surface and mechanical strength of threaded female connectors, as exposed bolts affect the appearance and diagonal screwing can damage screw-threads, while hidden nuts make axial alignment difficult.
Innovation Solution
Bolts are inserted from the lower surface of the shell and threaded with recessed parts inside the hoop structure, avoiding exposure and using sealing members and loosely fitted nuts to ensure proper alignment and tension adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If bolts are inserted from the striking surface side to connect the hoop to the shell, then the mechanical connection is simple and direct, but the bolt heads are exposed and adversely affect the cosmetic appearance of the striking surface
Solution Approach 1:
The patent inverts the traditional bolt insertion direction by inserting bolts from the lower surface side of the shell rather than from the striking surface side. This allows the bolt heads to be hidden on the non-visible lower surface while the threaded portions engage with nuts on the hoop's inner surface, achieving both aesthetic appearance and mechanical connection without exposing fasteners on the striking surface.
2Device complexity
If threaded female connectors are formed directly in the hoop structure from resin material, then the connection structure is simplified, but the screw-threads can be damaged and wear out when bolts are screwed in diagonally
Solution Approach 1:
The patent segments the threaded connection function into separate components: male threaded portions on the bolts and female threaded connectors (nuts) as distinct elements. The nuts are fitted into recessed parts formed in the hoop structure, separating the load-bearing threaded engagement from the hoop body itself. This segmentation allows the resilient nut to accommodate diagonal bolt insertion while maintaining reliable threaded connection.
Solution Approach 2:
The patent changes the material parameter of the female threaded connector from resin (hoop material) to metal (nut material). The nuts are made of metal and fitted into recessed parts of the resin hoop, providing higher strength and durability to the threaded connection while the hoop structure remains as the primary resonant element.
3Strength
If nuts are fixedly bonded to the hoop structure to connect bolts, then the mechanical strength of connection is improved, but the hidden nuts make it difficult to axially align and screw the bolts
Solution Approach 1:
The patent uses a nested structure where the nuts are fitted inside recessed parts formed in the hoop structure. The recessed parts provide a cavity that accommodates the nuts, allowing them to be positioned and aligned properly during assembly. This nesting arrangement maintains the mechanical strength of fixed connection while enabling easier axial alignment compared to fully embedded or surface-mounted nuts.
4Strength
If the hoop structure is made with sufficient radial dimension to accommodate recessed parts, then the structural integrity is maintained, but the hoop might more likely be struck by error during performance
Solution Approach 1:
The patent applies local quality by creating recessed parts only in specific locations on the hoop structure where connection is needed, rather than uniformly thickening the entire hoop. The recessed parts are localized features that accommodate nuts without significantly increasing the overall radial dimension or surface area of the hoop that could be accidentally struck.
Data Source
AI summary
A percussion instrument includes a mainframe having a bottom part defining a lower surface. A head is tensioned over an inner part of the mainframe. A hoop structure is arranged over the outer periphery of the head and applies tension to the head. The hoop structure has a lower surface provided with a plurality of recesses. Female threaded connector parts are contained within the recesses. A plurality of bolts extend through the bottom part of the mainframe and engage the female threaded connector parts, to affix the hoop structure to the mainframe. The bolts extend into the bottom part of the mainframe, such that exposure of the bolts on the upper surface side of the hoop structure can be avoided.