Harpsound Chest Structural Stability via Interlocking Bridges
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Solution Overview
Problem
Concert harps suffer from poor reproducibility and reliability due to empirical design and manufacturing methods, leading to structural instability, deformation, and aesthetic issues in the sound chest, which affects the instrument's stability and tuning.
Innovation Solution
The sound chest design features bridges partially glued to the internal surface of the shell with complementary transverse profiles for enhanced mutual engagement, increasing bending and rotational rigidity, and using a template for precise assembly and bonding with screws, eliminating the need for external bands and improving formability and timbre.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the shell is bent and glued to the bearing structure with a vacuum press and heating system, then the bonding speed is improved, but the shell is subjected to implosive stresses causing deformation and structural instability
Solution Approach 1:
The invention applies preliminary reinforcement measures by adding transverse bands to the internal surface of the shell before the gluing process. These bands pre-resist the implosive stresses that will occur during vacuum press bonding, preventing deformation and maintaining structural stability throughout the bonding process
Solution Approach 2:
The invention creates a composite structure by combining the shell material with reinforcing transverse bands and the bearing structure. This composite construction increases the overall rigidity and resistance to implosive stresses, allowing the shell to maintain its shape during high-speed vacuum press bonding
2Strength
If transverse members or small bands are glued to the internal surface of the shell to increase rigidity, then the shell rigidity is improved, but the device complexity and manufacturing steps increase
Solution Approach 1:
The invention merges the function of transverse stiffening members with the shell structure itself by integrating the bands into the shell's internal architecture. This combination achieves the necessary rigidity while reducing the number of separate components and simplifying the manufacturing process compared to adding discrete transverse members
3Strength
If the shell shape is swelled up like a barrel to increase bending strength, then the bending strength is improved, but manufacturing defects such as delamination, voids, and wrinkles increase
Solution Approach 1:
The invention applies local reinforcement through strategically placed transverse bands at specific locations on the shell's internal surface. This provides enhanced bending strength where needed without requiring a barrel-shaped swelling of the entire shell, thereby avoiding the manufacturing defects associated with global shape modification
4Manufacturing precision
If manual scraping and sanding is performed to eliminate manufacturing defects, then the surface quality is improved, but the manufacturing time and productivity decrease
Solution Approach 1:
The invention performs preliminary action by designing the shell and reinforcement structure to prevent manufacturing defects such as delamination, voids, and wrinkles from occurring in the first place. This preventive approach eliminates the need for subsequent manual scraping and sanding, significantly improving manufacturing efficiency while maintaining high surface quality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the structural stability and reproducibility of the sound chest, reducing deformation and improving the instrument's sound quality and manufacturing efficiency.
Implementation Method 1
said bridges are at least partially glued to the internal surface of the shell of the chest
Implementation Method 2
the mutual engagement portions of the bridges and the battens have substantially complementary transverse profiles, at least partially interpenetrated with each other
Implementation Method 3
using a template for precise assembly and bonding with screws
Data Source
AI summary
Sound chests having a sound board connected to a hollow body which includes a bearing structure to which there is connected an outer shell are provided. In such sound chests the bearing structure includes a bottom wall or chest-bottom, and a top member or upper block, a central longitudinal batten or backboard, and two side battens or planks, which extend between the chest-bottom and the upper block, remote from and close to the sound board, respectively; and a plurality of longitudinally staggered, transverse stiffening members or bridges each of which is connected centrally to the backboard with its ends connected to the side planks. Methods for making such sound chests are also provided.