Screw Fastener Engagement Release for Defined Preload Tightening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fastener connections rely on torque wrenches to apply pre-load forces, but this method is unreliable due to frictional forces and variability in torque wrench accuracy, leading to potential connection failures.
Innovation Solution
A fastener arrangement featuring a main body with a central axis, a head, and a shaft that lengthens to release engagement, allowing defined pre-load control independent of friction and torque wrench availability, with a driving element that positively engages in a rotational direction and releases when the first shaft section lengthens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque wrenches are used to apply pre-load forces, then fastener connections can be tightened, but the tightening reliability deteriorates due to frictional forces and torque wrench accuracy variability
Solution Approach 1:
The patent replaces the torque wrench mechanical system with a controlled lengthening mechanism. Instead of applying torque through a wrench that suffers from friction and accuracy issues, the invention uses a shaft section that lengthens by a controlled amount (e.g., 0.5mm) to directly release the driving element, providing a more reliable and precise method for achieving the desired pre-load force.
Solution Approach 2:
The invention changes the control parameter from torque (which is difficult to measure precisely) to shaft lengthening distance (which can be controlled more accurately). By controlling the lengthening of the shaft section by a specific amount, the system achieves reliable pre-load application without the measurement precision problems associated with torque wrenches.
2Ease of operation
If torque wrenches are used to control tightening, then pre-load forces can be applied, but the process complexity increases due to dependency on external tools and friction management
Solution Approach 1:
The fastener arrangement performs the tightening control function itself through the controlled lengthening of the shaft section. The system is self-sufficient and does not require external torque wrenches or complex friction management, thereby simplifying the operation while integrating the control mechanism within the fastener assembly.
Solution Approach 2:
The invention extracts the tightening control function from the external torque wrench and integrates it into the fastener arrangement itself. By removing the dependency on external tools and the complex friction management required by traditional torque-based systems, the solution simplifies both the operation and the overall system complexity.
3Reliability
If the shaft section is designed to release engagement after lengthening, then defined pre-load is achieved, but the structural complexity increases
Solution Approach 1:
The patent introduces a dynamic element (the lengthening shaft section) that transitions from a constrained state (engaged with the driving element) to a released state (disengaged after lengthening). This dynamic behavior allows the system to automatically control the pre-load and then release, achieving reliable pre-load control through a relatively simple structural change rather than complex control mechanisms.
Data Source
Figure 1~3b
AI summary
A fastener arrangement (100) for establishing a screw-connection comprising a main body (1) with a central axis (10) having a head (11) and a shaft (12) protruding from the lower side of the head in direction of the central axis (10), and having at its end facing away from the head (10) a thread (13), a driving element (2) penetrated by the shaft (12) and abutting with an upper end against the lower side of the head (11), wherein the driving element (2) positively engages with the main body (1) in a rotational direction around the central axis (10) in screw-in direction of the thread (13). The positive engagement between the main body (1) and the driving element (2) is designed such that if a first shaft section (121) of the main body (1) that penetrates the driving element (2) lengthens to a certain extent in the indented use of the fastener arrangement (100), the positive engagement is released.