Hex Driver Non-Linear Sidewalls Torque Distribution
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Solution Overview
Problem
Existing fastener driving tools often cause premature fatigue and stripping of internal hex fasteners due to high stress concentrations at point contact areas, leading to deformation and failure.
Innovation Solution
The design of a hexagonal driver with non-linear sidewalls and corner flats that distribute stress over a larger area, providing an offset angle to engage corner flats instead of single-point contact, reducing stress on the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a point contact engagement is used between the driver and fastener, then the tool can impart torque to the work piece, but the fastener becomes prematurely fatigued and stripped due to high stress concentrations
Solution Approach 1:
The driver geometry is segmented into multiple contact zones along the sidewalls, transitioning from a single point contact to multiple distributed contact points. This segmentation distributes the torque transmission across several locations, reducing stress concentration at any single point while maintaining effective torque delivery to the fastener
Solution Approach 2:
The invention transitions from point contact (zero-dimensional) to line contact (one-dimensional) by introducing curved sidewalls with multiple contact zones. This dimensional change allows the driver to engage the fastener along a curved path, distributing stress across a larger area and improving fastener durability while maintaining torque transmission capability
2Ease of manufacture
If a traditional hexagonal driver with linear sidewalls is used, then the structure is simple and easy to manufacture, but the contact area with the fastener is small leading to high stress concentrations
Solution Approach 1:
The driver sidewalls are designed with curved profiles instead of linear edges, creating a rounded geometry that naturally distributes contact stress across a larger area of the fastener. This curvature modification increases the contact area and reduces peak stress concentrations while remaining compatible with standard manufacturing processes
Solution Approach 2:
The invention modifies the geometric parameters of the driver, specifically the sidewall curvature radius and contact zone distribution, to optimize stress distribution. By adjusting these geometric parameters, the driver achieves reduced contact stress and improved fastener durability without significantly complicating the manufacturing process
Data Source
AI summary
The present invention relates to tools, for example, hexagonal drivers and bits adapted to engage fasteners. The tool includes an external geometry that is adapted to engage internal walls or flats of a fastener with a larger area compared the prior designs that use a point type of contact. This reduces the stress exerted on the fastener and damage or deformation to the internal walls of the fastener.