Hold Down Fastener Assembly Locking Mechanism
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Solution Overview
Problem
Prior art hold down systems in wood frame construction face issues with uplift resistance and wood shrinkage, as well as compromised integrity due to shifting resilient members under load conditions, and inadequate bearing contact when the tie-rod is not installed perpendicular to the horizontal surface.
Innovation Solution
A fastener assembly with a movable cylindrical member and a spring-urged locking mechanism, featuring a resilient member captured between specific receiving volumes that prevent shifting out of the locking position, ensuring secure engagement and maintaining axial tension even when the tie-rod is slightly off-vertical.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a resilient member is manipulated between opposing circumferential grooves to allow axial movement and locking, then the fastener assembly can accommodate wood shrinkage and compression loading, but the resilient member may shift out of its locking position under load conditions, compromising the integrity of the fastener assembly
Solution Approach 1:
The fastener assembly is divided into distinct functional segments: a first cylindrical member, a second cylindrical member, and a resilient member. Each segment has a specific function - the first member provides structural support, the second member allows axial movement, and the resilient member provides locking capability. This segmentation allows each component to be optimized for its specific function while working together to resolve the contradiction between adaptability and reliability.
Solution Approach 2:
The resilient member is nested within the second cylindrical member, which itself is nested within the first cylindrical member. This nested structure allows the resilient member to be contained and guided by the cylindrical members, preventing it from shifting out of position under load while still allowing it to manipulate between grooves for locking and unlocking operations.
2Ease of operation
If the tie-rod is not installed perpendicular to the horizontal bearing surface, then field installation conditions are accommodated, but the fastener assembly may not sit squarely on the bearing surface, losing bearing contact and compromising holding capacity
Solution Approach 1:
The fastener assembly incorporates dynamic elements that allow it to adjust to non-perpendicular installation angles. The resilient member can deform and the cylindrical members can shift slightly to accommodate angular misalignment, ensuring that the assembly remains functional even when the tie-rod is not perfectly perpendicular to the bearing surface.
Solution Approach 2:
The design allows for changes in geometric parameters under load. When the tie-rod is installed at an angle, the fastener assembly can shift its internal components and bearing surfaces to redistribute loads and maintain adequate contact, effectively changing its operational geometry to compensate for the non-perpendicular installation.
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 solution enhances the holding capacity and integrity of the fastener assembly by maintaining axial tension and preventing the resilient member from shifting under load conditions, ensuring effective uplift resistance and accommodating wood shrinkage and compression loading.
Implementation Method 1
A spring is operably attached to the first and second cylindrical members to urge the one in the first direction
Implementation Method 2
A resilient member is disposed between the first and second cylindrical walls. One of the first and second cylindrical walls includes a first receiving volume configured to fully receive the resilient member and the other cylindrical wall includes a plurality of second receiving volumes configured to only partially receive the resilient member
Data Source
AI summary
A fastener assembly comprises a first cylindrical member disposed within a second cylindrical member. One is movable relative to the other one in a first direction, and locked in a second direction opposite to the first direction. A spring is operably attached to the members to urge the one in the first direction. The members include opposing first and second cylindrical walls, respectively. A resilient member is disposed between the walls. One of the walls includes a first receiving volume configured to fully receive the resilient member and the other wall a plurality of second receiving volumes configured to only partially receive the resilient member. The resilient member is shifted between the first and second receiving volumes such that the one can move in the first direction but locked in the second direction; and the first and second receiving volumes are configured such that the resilient member is captured within a locking volume formed between the first volume and an opposing second volume when the first and second cylindrical members are locked together, the locking volume having an entrance opening that prevents the resilient member from shifting out of the locking volume and into the first receiving volume.