Compound Fastener Recess Geometry for Wobble and Stripping Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fasteners with hexalobular recesses suffer from undesirable wobble and stripping when driven by tools, due to interference between the tool and the hexalobular recess, leading to inadequate engagement and stability.
Innovation Solution
A fastener design featuring a stacked compound recess with a hexalobular first recess and a rectilinear second recess, where the stability surface is oriented at an angle greater than 1° and less than or equal to 89° relative to the major axis, allowing a tool to engage both recesses and reduce wobble by increasing torque application without stripping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hexalobular recess is used to allow greater torque application, then torque transmission capability is improved, but wobble and stripping occur due to interference between the tool and recess
Solution Approach 1:
The recess is divided into multiple segments or surfaces with different orientations. The hexalobular recess includes stability surfaces oriented at specific angles (greater than 1° and less than or equal to 89° relative to the major axis) that segment the contact areas, allowing the tool to engage multiple surfaces that reduce wobble while maintaining torque transmission capability.
2Stability of the object's composition
If the recess shape is modified to reduce wobble, then stability is improved, but torque application capability may be reduced
Solution Approach 1:
The recess employs asymmetric stability surfaces with specific angular orientations (greater than 1° and less than or equal to 89° relative to the major axis) that are not symmetrically distributed. This asymmetric configuration provides stable tool engagement and wobble control while maintaining the hexalobular shape's torque transmission properties.
3Stability of the object's composition
If the tool engagement depth is increased to improve fit, then stability is improved, but the risk of stripping increases without proper recess design
Solution Approach 1:
The recess is designed with stability surfaces oriented at predetermined angles (greater than 1° and less than or equal to 89° relative to the major axis) that prepare the geometry for optimal tool engagement. This preliminary geometric configuration ensures that as the tool is inserted to deep engagement (at least 90% of total recess depth), the stability surfaces guide the tool and distribute loads to prevent stripping.
Data Source
AI summary
A fastener including a first recess and a second recess adjacent the first recess. The first recess includes a side surface defining a shape of the first recess and a stability surface oriented at an angle of greater than 1° and less than or equal to 89° relative to a major axis of the fastener.