Multilobed Recess Torque Strength via Curved Lobes
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Solution Overview
Problem
Existing fixing members with multilobed recesses are limited in the maximum torque they can withstand without causing deformation, particularly in the tips of tightening or removing tools, restricting their assembly torque capacity.
Innovation Solution
A fixing member with a threaded end featuring a multilobed recess, where each lobe is defined by a continuous series of three arcs of a circle, and a complementary male element with a raised shape, both designed to distribute stress and increase torque strength without causing deformation, allowing for higher torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multilobed recess is used in the fixing member, then the torque transmission capability is improved and tool deformation is reduced, but the maximum torque capacity is still limited beyond which excessive deformation occurs
Solution Approach 1:
The recess is designed with a curved peripheral edge instead of straight edges, creating a multilobed shape with rounded contours. This curvature distributes stress more evenly across the tool-recess interface, preventing stress concentration at sharp corners and enabling higher torque transmission without tool deformation
Solution Approach 2:
The recess peripheral edge is segmented into multiple lobes (at least three), creating multiple contact zones between the tool and fixing member. This segmentation increases the surface area for torque transmission and distributes the mechanical load across multiple regions, enhancing overall torque capacity while reducing localized deformation
2Ease of manufacture
If the recess peripheral edge is formed with straight edges and corners, then manufacturing is simpler, but stress concentration occurs leading to cracks and reduced torque capacity
Solution Approach 1:
The peripheral edge of the recess is designed with continuous curved lines forming multiple lobes, eliminating sharp corners and straight edges. This curvature prevents stress concentration points where cracks would initiate, allowing the structure to withstand higher torques without cracking while maintaining manufacturing feasibility through appropriate forming processes
3Ease of operation
If a hexagonal recess is used, then the fixing member can be assembled, but the torque capacity is limited and tool deformation occurs at relatively low torque levels
Solution Approach 1:
The recess is designed with multiple lobes (at least three) around its peripheral edge, creating multiple contact zones with the tool. This segmentation increases the effective surface area for torque transmission compared to a hexagonal shape, distributing the mechanical load more effectively and enabling higher torque capacity before tool deformation occurs
Solution Approach 2:
The lobes of the recess are formed with curved peripheral edges rather than straight lines, creating a more optimized stress distribution pattern. This curvature allows for better stress dispersion during torque application, increasing the maximum torque the assembly can withstand before tool deformation occurs
Data Source
AI summary
A fixing member comprises a threaded end, one end face of which contains a recess capable of housing a tip, complementary in shape, said recess comprising a peripheral edge in the form of a multilobed continuous curved line. The cross-section of each lobe L is defined by a continuous series of three arcs of a circle, i.e. a first convex arc of a circle with a first radius (R1), on either side of which a second concave arc of a circle with a second radius (R2) are positioned. Each lobe is connected to the adjacent lobe via a third convex arc of a circle with a third radius (R3, R3u) larger than the first radius (R1). The invention also relates to a male element with a raised shape complementing that of the recess, in addition to a handling tool and a testing gauge comprising such a male element.