Hexalobular Fastener Recess Geometry for Wobble-Free Torque Transfer
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Solution Overview
Problem
Existing fasteners with hexalobular recesses suffer from wobble and stripping issues when torque is applied, due to interference between the tool and the fastener's lobe, leading to reduced torque application and stability during driving.
Innovation Solution
A fastener design featuring a hexalobular recess with an enlarged inner lobe surface radius and diameter, allowing a tool with a tapered side to insert deeper and engage more effectively, minimizing wobble and enabling higher torque application by avoiding interference with the tool's side surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hexalobular recess is used to apply greater torque, then torque application capability is improved, but tool wobble and stripping occur due to interference between the tool and fastener lobe
Solution Approach 1:
The patent modifies the geometric parameters of the hexalobular recess by increasing the inner lobe surface radius to a specific range (0.234A ≤ Ri ≤ 2.165A, where A is the outer diameter). This parameter change allows the tool to insert deeper and engage more effectively, reducing wobble and preventing stripping while maintaining high torque application capability.
2Reliability
If the inner lobe surface radius is increased to reduce wobble, then tool engagement is improved, but the recess geometry becomes more complex
Solution Approach 1:
Rather than fundamentally changing the recess geometry, the patent optimizes existing parameters within the hexalobular configuration. The inner lobe surface radius is adjusted to a specific range, which improves tool engagement without requiring a complete redesign of the recess shape, thus limiting the increase in geometric complexity.
3Stability of the object's composition
If the tool inserts deeper into the recess to minimize wobble, then stability is improved, but the inner diameter and lobe surface dimensions must be precisely controlled
Solution Approach 1:
The patent establishes specific parameter ranges for the inner lobe surface radius (0.234A ≤ Ri ≤ 2.165A) and inner diameter (0.72A ≤ B ≤ 0.85A, where B is the inner diameter). These defined ranges provide clear manufacturing targets that balance the need for deep tool insertion with achievable dimensional control, reducing wobble while maintaining manufacturability.
Data Source
AI summary
A fastener including a shank extending in a direction along a major axis; and a head comprising a hexalobular recess, wherein the hexalobular recess has an inner lobe surface having a radius satisfying0.234A≤Ri≤2.165A, wherein A is an outer diameter of the hexalobular recess, and Ri is the radius of the inner lobe surface.