Eyeglass Hinge Screw Part with Elastic Radial Elevation Structures
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Solution Overview
Problem
Existing screw parts for connecting eyeglass components, such as middle parts to earpieces, face challenges in accurately adjusting friction torque due to manufacturing tolerances, leading to undesirable earpiece movement or difficulty in operation, and are prone to falling out during screwing due to insufficient initial friction.
Innovation Solution
A screw part with a shank featuring an external thread and a sleeve with radial elevation structures along its outer circumference, providing a defined friction torque that is independent of sleeve length tolerances, allowing precise adjustment and compensation for out-of-round boreholes, and reducing fatigue in long-term use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a smooth outer circumferential face of the sleeve is used, then insertion into the borehole is easy with minimal friction torque, but the friction torque cannot be sufficiently adjusted and the screw part may fall out during screwing
Solution Approach 1:
The sleeve is designed with radially outwardly projecting elevation structures at specific locations on its outer circumferential face, creating localized high-friction zones. These elevation structures have elastic structural elements that deform under load to engage with the borehole wall, providing controlled friction torque at specific points while maintaining smooth insertion paths between them.
Solution Approach 2:
The elevation structures are pre-configured with elastic structural elements that automatically deform and engage with the borehole wall upon insertion, generating the required friction torque before the screwing operation begins. This preliminary engagement prevents the screw part from falling out during assembly.
2Reliability
If the sleeve length is increased to improve friction torque through compression and thread engagement, then friction torque increases, but manufacturing tolerances cause variability in the actual friction torque
Solution Approach 1:
Instead of relying on the overall sleeve length and compression, the friction torque is generated by localized elevation structures with elastic structural elements. The friction torque depends on the deformation of these elastic elements and their engagement with the borehole wall, not on the total sleeve length. This makes the friction torque insensitive to manufacturing tolerances in sleeve length.
Solution Approach 2:
The design shifts the critical parameter from sleeve length to the geometry and elastic properties of the elevation structures. By controlling the shape, size, and material properties of the elastic structural elements in the elevation structures, the friction torque can be precisely adjusted without being affected by variations in sleeve length during manufacturing.
3Reliability
If the sleeve diameter is increased to improve friction torque, then friction torque increases, but the sleeve becomes less elastic and harder to insert
Solution Approach 1:
The sleeve's outer circumferential face is segmented into elevation structures with elastic structural elements rather than being a continuous smooth surface. This segmentation allows localized elastic deformation at the elevation structures to generate friction torque, while the rest of the sleeve maintains its original diameter and elasticity for easy insertion.
Solution Approach 2:
The elastic properties are concentrated in the structural elements of the elevation structures rather than being distributed throughout the entire sleeve. This localized elasticity provides the necessary friction torque through controlled deformation at the elevation structures, while the overall sleeve remains slender and easy to insert into the borehole.
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 screw part ensures a consistent and adjustable friction torque, preventing earpiece fall-off and operational difficulties, while reducing the need for compression or engagement with internal threads, thus enhancing the reliability and usability of eyeglass hinges.
Implementation Method 1
the at least one radial elevation structure also has an extent, on the outer circumferential face of the sleeve along the longitudinal direction, that is greater than a width of the at least one structural element, preferably greater than a width of the elevation structure. The screw part has advantages over the prior art. In particular, the radial elevation structure, unlike the situation with a smooth circumferential face, already provides a friction torque, which may be defined with great accuracy due to the specific design of the radial elevation structure, during insertion of the screw part into a borehole.
Implementation Method 2
With the aid of the radial elevation structure, it is also possible to compensate for out-of-round eccentricities of a borehole into which the screw part is inserted.
Implementation Method 3
When the screw part is screwed into an internal thread, the sleeve at a distal end also comes into engagement with the internal thread, so that the sleeve is compressed, at least in areas. Due to the resulting expansion of the sleeve, viewed in the radial direction, on the one hand, and the engagement of the sleeve with the thread on the other hand, a friction torque results
Data Source
AI summary
A screw part has a shank with a threaded portion having at least one external thread turn, and a sleeve that surrounds the shank in a circumferential direction around more than three-fourths of the circumference. The sleeve extends along a sleeve portion in a longitudinal direction of the shank. The sleeve has at least one radial elevation structure on an outer circumferential face. The at least one radial elevation structure has at least one structural element that has an elastic design in the radial direction. The at least one radial elevation structure has an extent, on the outer circumferential face of the sleeve along the longitudinal direction, that is greater than a width of the at least one structural element.