Tapping Screw Anti-Loosening via Asymmetric Thread Protrusions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional tapping screws fail to reliably prevent loosening, especially when workpieces expand, contract, or oscillate, due to inadequate anti-loosening effects.
Innovation Solution
The tapping screw features an asymmetric normal thread with engaging protrusions on the clearance groove edges and a shaft with arc-shaped parts, embedding a larger workpiece portion into clearance grooves and circumferential surfaces, enhancing anti-loosening by compressing and embedding workpiece material effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional clearance grooves are provided on the external thread, then some anti-loosening effect is achieved, but the anti-loosening effect is insufficient to reliably prevent loosening under thermal or mechanical changes
Solution Approach 1:
The external thread is segmented into multiple functional zones: normal thread portions for fastening, clearance grooves for workpiece embedding, and engaging protrusions for enhanced locking. This segmentation allows each zone to perform its specific function, creating a multi-stage anti-loosening mechanism that reliably prevents loosening under thermal expansion, contraction, or oscillation while maintaining manufacturing feasibility through systematic structural division
Solution Approach 2:
The engaging protrusions are positioned asymmetrically on specific edges of the clearance groove bottoms, creating uneven engagement patterns that enhance anti-loosening effectiveness. The asymmetric design ensures that workpiece material embeds more effectively into the clearance grooves during tightening, and the engaging protrusions provide additional mechanical interlocking that prevents back-out, particularly under oscillating loads
2Reliability
If the shaft part has a complex cross-sectional shape with arc-shaped parts, then the anti-loosening effect is enhanced through workpiece embedding, but the manufacturing difficulty increases
Solution Approach 1:
The shaft part cross-section incorporates arc-shaped portions with different curvature radii that connect to form a continuous curved profile. This curved geometry enables workpiece material to be compressed and embedded into the circumferential surface during tightening, creating friction-based anti-loosening. The curved design is manufacturable using standard forming processes and provides effective mechanical interlocking without requiring complex multi-step manufacturing operations
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 solution provides an excellent anti-loosening effect, ensuring the screw remains securely threaded even under thermal or mechanical changes, such as expansion, contraction, or oscillation, by embedding workpiece material deeply into clearance grooves and circumferential surfaces.
Implementation Method 1
portions of the workpiece that are compressed by the external thread when the internal thread is formed, are embedded into the clearance grooves
Implementation Method 2
a portion of workpiece, which is compressed by the external thread when an internal thread is formed in the hole of the workpiece, is embedded into each clearance groove
Implementation Method 3
the engaging protrusion being embedded into the portion of the workpiece that has been embedded into the clearance groove
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed herein is a tapping screw (1) exerting an excellent anti-loosening effect with regard to a workpiece made of a soft material such as resin and an aluminum alloy. The tapping screw (1) includes a shaft part (3), and a normal thread (10) which is formed on the outer circumferential surface of the shaft part. A clearance groove (20) is formed by cutting out a portion of a ridge of the normal thread, and an engaging protrusion (30) is provided on a bottom of the clearance groove along a portion or an entirety of an edge of the bottom that continuously extends from a flank surface of the normal thread. The tapping screw (1) exerts an excellent anti-loosening effect even when a workpiece expands, contracts or oscillates because the engaging protrusions (30) are embedded into portions of the workpiece which have been embedded into the clearance grooves (20).