Dual-Thread Fastener Assembly for One-Step Depth Adjustment
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Solution Overview
Problem
Existing fastening systems for insulation layers on steel sheet structures face challenges in adjustability and rotational loading during the final mounting phase, leading to adverse effects on extraction forces and film loading.
Innovation Solution
A fastener with opposing thread directions (right-hand and left-hand threads) and a stop mechanism, combined with a nut, allows for controlled placement depth and rotation without forcing the grommet to rotate, preventing undesired rotational movement and ensuring secure anchoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a hexagonal nut is added to the fastener thread to improve adjustability of placement depth, then the settability of placement depth is improved, but the head widening of the grommet exerts an undesired rotational driving movement on the film during final mounting
Solution Approach 1:
The patent applies opposite thread directions (right-hand and left-hand threads) on different sections of the fastener shaft. This inversion of thread direction allows the fastener to rotate in one direction while the opposing threads prevent the grommet from rotating, thereby eliminating the harmful rotational movement on the film while maintaining adjustability through the nut mechanism
2Reliability
If the fastener is drilled into the substructure through insulation layers to secure them, then the insulation layers are efficiently fastened, but in sheet-metal substructures the engagement is very narrow and high stresses are formed through the thread
Solution Approach 1:
The fastener shaft is divided into two distinct thread sections with opposite thread directions. This segmentation allows each thread section to serve a specific function: one section engages with the nut for adjustment while the other provides secure anchoring in the substructure, distributing stresses more effectively and preventing over-tightening that would cause high localized stresses
3Force
If adjustment by turning-forward or turning-back of the fastener is performed to control tensile loads, then tensile load control is achieved, but the extraction forces of the fastener are adversely affected
Solution Approach 1:
The fastener system incorporates a dynamic adjustment mechanism using a nut that can be rotated along the threaded shaft to control placement depth and tensile loads. The opposing thread directions ensure that during final tightening, the fastener rotates without causing the grommet to rotate, allowing precise control of tensile loads while maintaining optimal extraction forces through controlled engagement
Data Source
AI summary
A fastening arrangement including a grommet, which is configured as a substantially cylindrical sleeve with a head part, with a hollow-cylindrical shaft and with a conical tip, and also a fastener and a nut, for example made of plastic, which is fitted on the first threaded portion of the fastener. The fastener has two threaded portions, wherein one threaded portion is configured as a right-hand thread and the other threaded portion is configured as a left-hand thread (or vice versa). Moreover, the invention comprises a mounting method for such a fastening arrangement, in which the setting operation (anchoring of the fastener, adjustment of the sheath) can be managed in one step without changing the driving direction of the setting tool.