Log Building Tie Bolt with Ratchet Spring Tensioning
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Solution Overview
Problem
Existing log building sealing methods fail to maintain the integrity of the wall structure due to uneven shrinkage of logs, leading to gaps and inadequate tension to resist residual stresses and wind forces, which result in bowing and separation of logs.
Innovation Solution
A log wall system with a tie bolt and coil spring mechanism, where the tie bolt is ratcheted to maintain tension and accommodate relative movement, using collets to secure the bolt and prevent separation, while a coil spring provides continuous downward force to keep logs engaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a simple compression spring is used between the nut and top plate, then initial compression of the sealant is provided, but the spring force is insufficient to resist residual stresses and wind forces causing log bowing and separation
Solution Approach 1:
The system transitions from a static rigid rod to a dynamic mechanism with a coil spring and ratchet. The spring provides continuous adaptive force that can accommodate log shrinkage while maintaining sealant compression, and the ratchet allows one-way movement to accommodate bowing while preventing separation.
Solution Approach 2:
The mechanism changes the physical state of the connection from fixed-length to variable-length through the combination of spring compression and ratchet engagement. This allows the system to adapt to changing log dimensions during drying while maintaining structural integrity.
2Stability of the object's composition
If a rigid threaded bar is used to tension the logs, then initial compression of the seal is achieved, but the rigid structure cannot accommodate shrinkage and stress-induced deformation
Solution Approach 1:
The rigid rod is replaced with a dynamic system comprising a coil spring and ratchet mechanism. This allows the connection to adapt its length and force application in response to log shrinkage and deformation while maintaining stability through the ratchet's one-way locking action.
Solution Approach 2:
The ratchet acts as an intermediary between the spring and the logs, mediating the interaction by allowing movement in one direction (accommodating shrinkage and bowing) while preventing movement in the opposite direction (preventing separation).
3Manufacturing precision
If logs are allowed to shrink freely, then natural drying occurs, but gaps form between logs requiring resealing
Solution Approach 1:
The system applies preliminary counteracting force through the pre-compressed spring to prevent gap formation before they occur. The spring continuously pushes the logs together, counteracting the separating force of uneven shrinkage and maintaining seal integrity throughout the drying process.
4Strength
If the tie bolt is secured rigidly at both ends, then structural stability is maintained, but relative movement between logs is inhibited causing stress concentration
Solution Approach 1:
The rigid fixed-end connection is replaced with a dynamic system where the ratchet allows controlled relative movement between logs while the spring maintains continuous compressive force. This prevents stress concentration by allowing stress relief through controlled movement while maintaining overall structural stability.
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
The system ensures continuous tension between logs, preventing separation and maintaining a tight seal as logs shrink, while allowing for relative movement to accommodate uneven shrinkage and stress-induced deformation.
Implementation Method 1
a spring acting between one of said fastenings and a log to induce tension in said tie bolt
Implementation Method 2
said one of said fastenings having a ratchet included therein to permit passage of the tie bolt against the bias of said spring and inhibit movement of said tie bolt under the bias of said spring
Data Source
AI summary
A tie bolt assembly for a log building has a coil spring that applies a continuous compressive load to force the logs together. Subsequent expansion or separation of the logs is prevented by a ratchet mechanism acting between the tie bolt and log.