Spiral Staircase Tread Mounting Plate Elastic Deformation
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Solution Overview
Problem
Spiral staircase treads often loosen due to vibrations caused by repeated use, leading to ineffective attachment methods such as hollow cylindrical collars and bolts, which fail to maintain secure fastening over time.
Innovation Solution
A tread mounting system featuring axially and angularly offset tread assemblies with mounting plates that have a first radius of curvature less than the mounting column's second radius, causing the plates to elastically deform and apply tension to the attachment hardware, such as carriage bolts, thereby preventing loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bolts are used to attach mounting plates to the column, then the attachment is initially secure, but repeated use causes vibrations that loosen the bolts
Solution Approach 1:
The mounting plate is pre-deformed to a smaller radius of curvature before attachment, so that when installed, it automatically applies tensile stress to the fasteners. This preliminary deformation ensures that the fasteners are pre-tensioned to prevent loosening from vibrations during use.
Solution Approach 2:
The mounting plate's radius of curvature is changed from its unstressed state (smaller radius) to its stressed state (larger radius matching the column). This parameter change creates elastic deformation that generates continuous tensile force on the fasteners, preventing vibration-induced loosening.
2Manufacturing precision
If the mounting plate has a radius of curvature equal to the column's outer diameter, then the attachment fits perfectly, but the plate cannot apply sufficient tension to prevent loosening
Solution Approach 1:
The mounting plate is designed with a radius of curvature that is initially smaller than the column's outer diameter. Upon installation, the plate elastically deforms to match the column's curvature, creating the necessary tensile stress in the fasteners while maintaining a precise fit.
Solution Approach 2:
The plate is pre-formed with a smaller radius of curvature before installation. This preliminary configuration allows the plate to automatically generate tensile stress in the fasteners through elastic deformation during installation, ensuring both precise fit and sufficient tension.
3Device complexity
If hollow cylindrical collars are used to attach treads, then the attachment is simple, but the collars cannot prevent loosening from vibrations
Solution Approach 1:
The mounting plate uses elastic deformation through radius of curvature changes to generate continuous tensile force on the fasteners. This simple parameter-based mechanism provides vibration resistance without complicating the overall mounting structure.
Solution Approach 2:
The mounting plate automatically generates the necessary tension in the fasteners through its own elastic deformation during installation and use. The system is self-regulating, requiring no additional components or complex mechanisms to prevent loosening.
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 securely attaches tread assemblies to the mounting column, maintaining tension in the fasteners and preventing loosening, ensuring a stable and secure spiral staircase structure.
Implementation Method 1
the mounting plate is in an elastically deformed (joint preload) state applying tension to the attachment hardware to inhibit loosening thereof
Data Source
AI summary
A method is disclosed of attaching a tread assembly of a spiral staircase to a vertical support column. One step of the method involves providing a tread assembly having a tread portion attached to an arcuate mounting plate defining at least one hole through which extends a fastener defining external threads, the mounting plate having a first face defining a first radius of curvature. Another step involves providing a support column extending along an axis, the support column having a plurality of axially and angularly spaced apart tread attachment locations, each of the tread attachment locations having an arcuate outer surface defining a corresponding aperture for receipt of the fastener, the arcuate outer surface defining a second radius of curvature that is greater than the first radius of curvature. According to another step of the method, the tread assembly is loosely connected to one of the tread attachment locations of the support column. According to another step, the fastener is tightened such that the arcuate mounting plate of the tread assembly is elastically deformed to be in substantial engagement with the tread attachment location and applies tension to the elongate fastener to inhibit loosening thereof.