Removable Mechanical Bolt Tensioner Eliminates Torsional Twist
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Solution Overview
Problem
Conventional methods for tensioning bolts/studs, such as torqueing and hydraulic systems, face issues like torsional twisting, high costs, and impracticality for smaller diameters, especially in confined spaces, and require bulky hydraulic components.
Innovation Solution
A removable mechanical tensioning system that uses an anti-rotation member and a tensioner device with a nut engaging assembly to axially stretch elongate members with lower torque, eliminating the need for additional tools and maintaining axial stretch without torsional twist.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional torqueing method is used to tension bolts/studs, then the bolt/stud can be tensioned axially, but torsional twisting occurs and accuracy deteriorates due to friction and varying friction coefficients
Solution Approach 1:
The tensioning process is segmented into two independent stages: first applying axial tension to stretch the bolt/stud, then separately securing the nut. This separates the tensioning function from the fastening function, eliminating the harmful coupling between axial tension and torsional twist that occurs in conventional single-step torqueing.
Solution Approach 2:
Instead of applying torque to the nut to achieve tension (conventional approach), the invention inverts the sequence by first applying direct axial tension to the bolt/stud and then securing the nut. This reverses the causal relationship between torque application and tension generation, eliminating torsional twisting as an intermediate step.
2Measurement precision
If hydraulic bolt tensioners are used to achieve accurate axial tensioning, then tensioning accuracy improves to within 5% of target, but the system becomes bulky and expensive requiring hydraulic cylinders, pumps and hoses
Solution Approach 1:
The invention extracts and eliminates the bulky hydraulic system components (cylinders, pumps, hoses) from the tensioning device, replacing them with a compact mechanical implementation that achieves the same axial tensioning function through direct mechanical engagement with the bolt/stud and nut.
Solution Approach 2:
The invention substitutes the hydraulic system with a purely mechanical system that uses direct mechanical engagement and leverage to apply axial tension to the bolt/stud and simultaneously secure the nut, eliminating the need for hydraulic fluid, pumps and hoses while maintaining tensioning accuracy.
3Device complexity
If conventional nuts are used with torqueing method, then the system is simple and inexpensive, but the accuracy of bolt tensioning deteriorates to within 25% range of target
Solution Approach 1:
The invention merges the tensioning function and the fastening function into a single integrated device that performs both axial tensioning of the bolt/stud and securing of the nut in one operation, eliminating the need for separate hydraulic equipment while maintaining high accuracy through the combined mechanical action.
Solution Approach 2:
The device uses the reaction force generated during nut engagement to automatically maintain the axial tension on the bolt/stud, making the system self-regulating and eliminating the need for complex external control systems while achieving accurate and consistent tensioning results.
4Measurement precision
If stay-on mechanical tensioning devices are used to tension bolts/studs, then axial tensioning is achieved, but separate expensive devices are required for each bolt/stud making the solution costly and inaccessible
Solution Approach 1:
The invention creates a universal tensioning device that can be applied to multiple bolts/studs of different sizes through adjustable components and interchangeable elements, allowing a single device to perform the function of multiple specialized devices, thereby reducing cost and increasing accessibility.
Solution Approach 2:
The device uses conventional nuts as the fastening element, copying the familiar and inexpensive nut design rather than requiring proprietary expensive stay-on devices, thereby maintaining compatibility with standard hardware while achieving improved tensioning accuracy through the integrated mechanical tensioning mechanism.
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 provides accurate and cost-effective axial stretching of bolts/studs with reduced torque requirements, making it accessible for smaller diameters and confined spaces, while being removable and preserving the axial stretch.
Implementation Method 1
a friction element; wherein the tensioning body is frictionally engaged to the base portion such that the tensioning body is freely displaceable relative to the base portion and the friction element in a transverse direction
Data Source
AI summary
The invention relates to a removable mechanical tensioning system, tool, and a method of stretching a bolt or stud axially, the bolt being located in and attachable to an object via a nut. The system in accordance with the invention comprises an anti-rotation member; and a tensioner device. The anti-rotation member is attachable to both the tensioner device and bolt. The tensioner device is operatively attachable to the bolt via the anti-rotation member. The tensioner device comprises or is operatively coupled to a nut engaging assembly configured to automatically engage and tighten the nut, at a lower torque than the applied tool torque. Displacement of a part of the tensioner device with a holding force applied to the anti-rotation member causes axial stretch of the elongate member and actuation of the nut engaging assembly to bring about displacement of the nut in the transverse direction relative to the stretched elongate member.