Wall Fixing Device With Rotating Arms For Stress Distribution
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Solution Overview
Problem
Existing wall fixings, such as wall plugs and toggle fasteners, are prone to failure under high loads due to stress concentration at the junction of the retaining means, which is perpendicular to the fastener aperture, leading to potential points of failure under significant pull-out forces.
Innovation Solution
A fixing device with a body and arms that rotate about the axis between retracted and extended positions, using a male-female mating connection and anti-rotation features to distribute stress, ensuring the arms are deployed by the fastener insertion, and featuring a clamping mechanism to secure the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the retaining means are oriented perpendicular to the wall and parallel to the fastener aperture, then the device can be inserted and deployed, but the pull-out force creates high stress concentration at the junction of the retaining means and shaft, leading to potential failure points
Solution Approach 1:
The patent inverts the orientation of the retaining means from being parallel to the fastener aperture (perpendicular to the wall) to being perpendicular to the fastener aperture (parallel to the wall). This reorientation changes the stress distribution so that pull-out forces act along the length of the retaining means rather than concentrating at the junction, thereby resolving the contradiction between ease of operation and strength.
2Ease of operation
If the retaining means are pivotable about axes perpendicular to the wall, then the device can be deployed from retracted to extended position, but the torque is applied about an axis normal to the axis of rotation, creating stress at the junction
Solution Approach 1:
The patent inverts the orientation of the pivot axes from being perpendicular to the wall to being parallel to the wall. This causes the torque from pull-out forces to be applied about the same axis as the rotation, rather than about a normal axis, thereby reducing stress concentration and improving reliability while maintaining the deployment mechanism.
3Reliability
If a two-step operation is used to actuate the retaining means before fastener insertion, then the device can be properly deployed, but the installation time increases when many devices need to be installed
Solution Approach 1:
The patent incorporates preliminary action by designing the retaining means to be automatically actuated during the fastener insertion process itself, rather than requiring a separate preliminary step. The fastener insertion automatically triggers the rotation of the retaining means from retracted to extended position, combining what were previously two separate steps into one, thereby improving productivity while maintaining reliable deployment.
Data Source
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AI summary
A fixing device for attaching a fastener to a wall, the device comprising a body having a fastener receiving aperture defined therein; and at least two arms pivotably mounted to the body between: a retracted position in which the device is insertable into an opening in a wall from a first side of the wall; and, an extended position in which the arms bear against a second side of the wall to inhibit removal of the device from the opening; in which the arms are configured to be retained in the extended position by a fastener inserted in the fastener-receiving aperture.