Two-Piece High-Strength Screw Assembly for Long Thin Fasteners
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Solution Overview
Problem
Existing high-strength screws face challenges in flexible and economical manufacturing, particularly for thin and long screws with a high length-to-thickness ratio, due to low production cycles and quality issues related to buckling rigidity and forming tool limitations.
Innovation Solution
A two-piece high-strength screw design with a materially separate head and shank, featuring a coupling recess and corresponding coupling element, which includes axial and torque transmission elements to prevent relative movement and ensure secure connection, allowing for efficient production through cold forming and heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-strength screws are manufactured as single-piece components using existing methods, then manufacturing simplicity is maintained, but production cycles are limited and quality issues occur due to buckling rigidity and material deformation
Solution Approach 1:
The screw is divided into two separate components: a head component and a shank component. The head component includes a coupling recess with axial and radial engagement features, while the shank component includes a coupling element with corresponding engagement features. These separate components are manufactured independently and then assembled together, allowing each component to be optimized for its specific manufacturing requirements and avoiding the buckling and deformation issues that occur in single-piece manufacturing of long, thin screws.
2Stability of the object's composition
If long, thin screws are manufactured as single-piece components, then structural integrity is maintained, but buckling rigidity issues arise during manufacturing
Solution Approach 1:
The screw is divided into a head component and a shank component that are manufactured separately and then assembled. This segmentation allows the shank to be produced without the buckling rigidity problems that occur during single-piece manufacturing of long, thin components, while the final assembled structure maintains the required structural integrity through the coupling elements.
Solution Approach 2:
The head and shank components are manufactured separately in advance, allowing each to be pre-hardened and processed to its final dimensions before assembly. This preliminary action eliminates the need to manufacture the entire screw in one piece, avoiding the buckling and deformation issues that occur during single-piece forming of long, thin screws.
3Ease of manufacture
If head and shank are manufactured as separate parts, then manufacturing flexibility and economy are improved, but additional assembly steps are required
Solution Approach 1:
The screw is segmented into a head component and a shank component that can be manufactured using different processes and materials optimized for each part's requirements. This segmentation provides manufacturing flexibility and economy, allowing pre-hardened materials to be used and reducing overall manufacturing costs despite the additional assembly step.
Solution Approach 2:
The coupling element and coupling recess act as intermediary features that facilitate the connection between the head and shank components. These coupling features include axial force transmission elements and torque transmission elements that enable reliable assembly while maintaining the benefits of separate manufacturing.
4Strength
If separate coupling elements are added to connect head and shank, then axial and torque transmission are achieved, but device complexity increases
Solution Approach 1:
The coupling element and coupling recess integrate multiple functions into unified structures. The coupling element includes both axial force transmission features (such as a shoulder or stop) and torque transmission features (such as splines, keys, or friction surfaces) combined in a single component. Similarly, the coupling recess integrates corresponding features to receive and secure the coupling element, achieving both axial and torque transmission without requiring separate components for each function.
Data Source
AI summary
High-strength screw (1), with a head (2) with a tool engagement contour (4), a shank (3) with a free end (5) pointing away from the head (2), a threaded section (6) with a thread (7) being arranged on the shank (3), the thread (7) being formed as a metric ISO thread or inch thread, the head (2) and the shank (3) being de-signed as materially separate parts, the head (2) having a coupling recess (8) arranged radially inside with an axial force transmission element (9) and a torque transmission element (10), the shank (3) having a coupling element (11) arranged radially outside on its outer circumference with an axial force transmission counter element (12) and a torque transmission counter element (13), the coupling element (11) engaging in the coupling recess (8), the axial force transmission element (9) and the axial force transmission counter element (12) being designed and arranged to positively interlock in such a way that an axial translatory movement of the head (2) relative to the shank (3) in the direction away from the free end (5) of the shank (3) is prevented or will be prevented, in particular non-releasably, and the torque transmission element (10) and the torque transmission counter element (13) being designed and arranged to interlock in such a way that a rotational movement of the head (2) relative to the shank (3) in the tightening direction of the thread (7) is or will be prevented.