Raised Torque-Absorbing Surfaces for Over-Torque Bolt Protection
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Solution Overview
Problem
The increased use of powered tools, such as impact wrenches, can lead to over-torquing of bolts, causing damage due to the high torque applied with little physical effort, necessitating a solution to increase bolt resistance to damage when using these tools.
Innovation Solution
A platform with raised surfaces, comprising plateaus and channels, is designed to contact fasteners, increasing the torque required to turn the fastener while minimizing the stress on the bolt, thereby protecting it from over-torquing damage. The raised surfaces are typically made of ductile iron and have a polygonal or round cross-sectional shape, with a smaller perimeter at the plateau than at the base, providing a sacrificial wear surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If powered tools like impact wrenches are used to tighten fasteners, then productivity increases and large torques can be applied with little physical effort, but the risk of over-torquing and bolt damage increases significantly
Solution Approach 1:
The raised surface acts as an intermediary element between the rotating fastener (nut or bolt head) and the stationary platform. This intermediary transfers torque from the rotating fastener to the stationary platform through friction contact on the raised surface, allowing the powered tool to apply torque without directly transmitting excessive forces to the bolt threads, thereby preventing over-torquing damage while maintaining high productivity
2Reliability
If a stationary platform with a raised surface is used to absorb torque, then bolt resistance to over-torquing damage increases, but the device complexity increases due to the additional platform structure
Solution Approach 1:
Instead of making the entire platform complex, only a localized raised surface is created on the stationary platform. This localized feature concentrates the torque-absorbing function in a specific area, providing bolt protection without requiring a completely complex platform structure. The rest of the platform remains simple and straightforward
Solution Approach 2:
The platform surface is segmented into a base surface and one or more raised surfaces. This segmentation allows the raised surface to specifically handle torque absorption while the base surface provides structural support, dividing the functions to achieve reliability without excessive overall complexity
3Reliability
If the raised surface is made harder than the fastener element, then the raised surface can serve as a sacrificial wear surface to protect the bolt, but the manufacturing precision requirements increase
Solution Approach 1:
The material hardness parameter of the raised surface is changed to be greater than that of the fastener element. This parameter change allows the raised surface to wear preferentially, serving as a sacrificial element that protects the bolt. The hardness parameter is specifically selected to achieve the desired wear characteristics while maintaining manufacturability
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 effectively increases the torque required to turn the fastener, thereby protecting the bolt from damage by increasing the time to failure when using powered tools, while maintaining effective bolt stress management until the raised surfaces are worn down.
Implementation Method 1
A plurality of raised surfaces project transversely to the base surface for contacting the fastener element. Each raised surface comprises a plateau... the raised surfaces may comprise ductile iron... providing a sacrificial wear surface
Data Source
AI summary
A plurality of raised surfaces on a platform absorb torque of a fastener contacting the surface while rotating relatively to the platform. Significant disproportionate increase in torque compared with the associated increase in bolt stress is observed by increased felt torque when tightening the fastener. Raised surfaces are used on lugs of a mechanical pipe coupling to increase the fastener's resistance to damage when powered tools are used to apply torque to the fastener.