Hexalobular Screw Head Conical Press Connection for Torque Stability
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Solution Overview
Problem
Existing screw driving systems fail to achieve a stable 'interference fit' with hexalobular screw heads, particularly with non-magnetic materials like Titanium and Stainless Steel, leading to screw instability and wobbling during one-handed operations, and are not cost-effective for large-scale production due to manufacturing tolerances and tool wear.
Innovation Solution
A conical press connection system with a hexalobular slot and tapered recess in the screw head, allowing for adjustable 'stick-fit' stability and absorption of manufacturing tolerances, featuring a tool with upper and lower engagement sections and a transition zone to ensure secure engagement without excessive tightness, suitable for various materials including softer ones like copper and aluminum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hexalobular slot with parallel upper peripheral wall is used, then the screw head can be engaged by the tool, but the screw cannot achieve adequate interference fit and stability
Solution Approach 1:
The patent applies conical geometry to the recess structure, replacing the traditional parallel-walled hexalobular slot with a conical press connection. The sloping transition surface and tapered recess create a curved, angle-based engagement surface that enables interference fit and stable connection between the tool and screw head, directly resolving the stability issue while maintaining structural simplicity.
2Reliability
If magnetic holder is used to hold the bit, then the screw can be supported, but this is not stable and satisfactory for professional users and non-magnetic materials
Solution Approach 1:
The patent replaces the magnetic holding system with a mechanical interference fit system. The conical press connection creates a purely mechanical engagement between the tool's lower engagement section and the screw head's tapered recess, eliminating dependence on magnetic properties and providing stable holding for all materials including non-magnetic ones like titanium and stainless steel.
3Reliability
If high degree of taper (2 1⁄2 - 3 1⁄2 DEG) is used in the recess, then the tapered bit can attain greater engagement, but the recess cannot be as deep as needed to prevent wobbling and requires vertical mounting
Solution Approach 1:
The patent optimizes the taper angle parameter of the recess, using a moderate angle (1-2 degrees) rather than the high degree of taper (2.5-3.5 degrees) in prior art. This parameter change allows the recess to be deeper while maintaining engagement effectiveness, preventing wobbling during manual and one-handed operations without requiring strict vertical mounting.
4Reliability
If tight interference fit is used, then the screw can be retained on the tool, but it is too tight for softer materials like copper, plastic, aluminium and titanium
Solution Approach 1:
The conical press connection provides a dynamic, adjustable interference fit that adapts to different material strengths. The sloping transition surface and tapered geometry allow the connection to be tight enough to retain the screw on the tool while being gentle enough not to damage softer materials, enabling universal applicability across different screw materials.
5Productivity
If conventional recess design is used, then manufacturing can proceed, but variations in tolerances and tool wear compromise the stick-fit quality
Solution Approach 1:
The conical press connection design inherently compensates for tolerance variations and tool wear through its geometric configuration. The sloping transition surface and tapered recess create a self-aligning, self-compensating mechanism that maintains stable stick-fit quality even as tools wear and manufacturing tolerances vary, ensuring consistent functional quality in large-scale production.
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 conical press connection system provides a stable and adjustable 'stick-fit' for screws of all materials, preventing wobbling and ensuring torque stability, even with one-handed operations, and enables cost-effective large-scale production by extending tool life and accommodating manufacturing variations.
Implementation Method 1
there is a 'stick fit' between the surface of the tapered recess and the external surface of the lower tapered engagement section
Data Source
Figure 1~3
AI summary
A system for driving a screw, comprising a screw and a corresponding tool, the screw head having a hexalobular slot (2) in the upper surface of the screw head, an upper peripheral wall (9) of hexalobular planform extending down into the screw head, the upper peripheral wall (9) being parallel or near parallel to the axis of the screw, a sloping transition surface (15) extending downwardly and inwardly with respect to the lower edge of the upper peripheral wall (9), and a tapered recess (11) extending downwardly from the lower edge of the sloping transition surface (15), in which the dimensions of the screw head are such that when the screw head is engaged by a tool (6) having upper (16) and lower (17) engagement sections, and in which the upper engagement section (16) is tapered downwardly at an angle with respect to the axis of the screw to which the tool is to engage and the lower engagement section (17) is tapered downwardly, so that there is a 'stick fit' between the surface of the tapered recess (11) and the external surface of the lower tapered engagement section (17), and there is no engagement with the sloping transition surface (15).