Spacer Fastener With Reversing Threads to Prevent Overtightening
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Solution Overview
Problem
Existing spacer fastening elements lack process reliability in ensuring consistent and secure connection between components, particularly in metal sheets, due to issues with thread engagement and overtightening.
Innovation Solution
A spacer fastener design featuring a self-drilling tip with alternating threaded sections that change direction of rotation to facilitate easy assembly, a stop element to prevent overtightening, and a thread-free area for secure axial fixation, ensuring a defined distance and firm connection between components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a drilling element with stop function is provided in the spacer fastening element, then pre-drilling is eliminated and assembly is simplified, but process reliability is reduced due to inconsistent thread engagement and overtightening risks
Solution Approach 1:
The threaded section is divided into two distinct parts: a first threaded section with first-direction threads for self-drilling and initial engagement, and a second threaded section with second-direction threads for forming the stop. This segmentation allows each section to perform its specific function optimally while maintaining process reliability.
Solution Approach 2:
The patent uses threads with opposite directions of rotation for the two threaded sections. The first threaded section has threads that engage during clockwise rotation (standard right-hand thread), while the second threaded section has threads that engage during counter-clockwise rotation (left-hand thread). This inversion enables the stop element to function reliably by controlling the rotation direction.
2Ease of operation
If the spacer fastening element uses alternating thread directions, then assembly is facilitated with easy rotation control, but device complexity increases due to multiple threaded sections
Solution Approach 1:
The patent combines multiple functions into a single spacer fastening element: the self-drilling tip creates the initial hole, the first threaded section provides self-tapping engagement, the second threaded section forms the stop element, and the thread-free area provides axial fixation. This merging eliminates the need for separate components while maintaining operational simplicity.
Solution Approach 2:
The spacer fastening element serves multiple purposes: it acts as a self-drilling screw, a spacer with defined distance, and a stop element all in one component. The alternating thread directions enable the single element to perform drilling, engagement, and stopping functions without requiring multiple separate parts.
3Productivity
If the distance from the end of the second threaded section to the tip is minimized, then the fastening process is quicker, but the first threaded section may not fully penetrate the first component
Solution Approach 1:
The patent specifies precise dimensional parameters for the threaded sections. The distance from the end of the second threaded section facing the tip to the tip is defined to ensure that the first threaded section completely penetrates the first component before the second threaded section begins to engage. This parameter control maintains both speed and precision.
4Reliability
If a thread-free area is provided between the first and second threaded sections, then overtightening protection is achieved, but the device complexity increases
Solution Approach 1:
The thread-free area is pre-designed in the spacer fastening element to provide overtightening protection before the fastening process completes. This preliminary structural feature ensures that once the first threaded section penetrates the fastening area, the spacer fastening element cannot be advanced further, preventing damage to the second component.
Data Source
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AI summary
The invention relates to a spacer fastening element (10, 30, 50, 70, 102) for fastening a first component (22, 42, 62, 104) at a distance from a second component (24, 44, 64, 106), comprising a head (16, 36, 56, 80, 116) which transitions into a shaft which in turn terminates in a self-drilling tip (11, 31, 51, 71), wherein a first threaded section (12, 32, 52, 72, 110) is provided downstream of the tip (11, 31, 51, 71) in the direction of the head (16, 36, 56, 80, 116), which has a thread with a first direction of rotation, wherein a hole is drilled into the first component (22, 42, 62, 104) by turning in the first direction of rotation. 104) can be inserted, through which the first threaded section (12, 32, 52, 72, 110) passes, and a stop element is provided downstream of the first threaded section (12, 32, 52, 72, 110), which forms a stop on the second component (24, 44, 64, 106). The invention is characterized in thatthat the stop element is designed as a second threaded section (14, 34, 54, 74, 112) which comprises a thread with a second direction of rotation opposite to the first direction of rotation, wherein the second threaded section (14, 34, 54, 74, 112) is designed such that when the spacer fastening element (10, 30, 50, 70, 102) is screwed in with the second direction of rotation, it can be screwed through the hole remaining in the first component (22, 42, 62, 104) after the penetration of the first threaded section (12, 32, 52, 72, 110), after which, while being screwed in with the first direction of rotation, it forms a stop on the second component (24, 44, 64, 106), wherein furthermore the area between the head (16, 36, 56, 80, 116) the outlet of the second threaded section (14, 34, 54, 74, 112) facing the head (16, 36, 56, 80, 116) is designed such that it can be guided through the remaining hole in the first component (22, 42, 62, 104) at least when rotating in the first direction of rotation.