Asymmetric Thread Impact Screw for Wood Fiber Protection
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Solution Overview
Problem
Existing screw technologies, such as symmetrical thread screws and screws with cutting points, are inefficient and cause fiber tearing during insertion, leading to prolonged installation times and difficulties in disassembly.
Innovation Solution
An asymmetric thread impact drivable screw with a ballistic point and unique thread design, featuring a long slide flank and short grip flank, minimizes fiber cutting by using a conical tip and low angle thread pitch, allowing for penetration without tearing wood fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If symmetrical thread screws with cutting points are used, then the screw can penetrate the material, but it causes fiber tearing and ripping during insertion
Solution Approach 1:
The patent applies asymmetry by designing threads with unequal flanks: a long slide flank at a shallow angle (10-20 degrees) that pushes fibers aside without cutting, and a short grip flank that provides holding power. This asymmetric thread geometry eliminates fiber tearing while maintaining penetration capability, directly resolving the contradiction between insertion speed and fiber damage.
Solution Approach 2:
The patent applies local quality by giving different functions to different parts of the thread: the long slide flank is optimized for fiber displacement with minimal cutting, while the short grip flank is optimized for holding power. This localized functional differentiation allows the screw to penetrate without tearing fibers while still achieving secure fastening.
2Strength
If regular nails or glue are used, then strong attachment is achieved, but disassembly becomes difficult or impossible
Solution Approach 1:
The patent applies segmentation by designing the thread as separable functional elements: the slide flank allows controlled insertion, while the grip flank provides holding power. The asymmetric geometry creates a one-way mechanical lock that maintains strong attachment but allows controlled removal, enabling both strong attachment and disassembly capability.
3Strength
If conventional screws are rotated into material, then connection is achieved, but installation time is extended
Solution Approach 1:
The patent applies periodic action through impact driving, where repeated impact forces drive the screw into the material rapidly. Combined with the asymmetric thread design that requires minimal rotation, this reduces installation time significantly while maintaining connection strength through the grip flank's holding power.
4Speed
If impact driving is used with prior art screw designs, then insertion speed is increased, but wood fibers are ripped and torn
Solution Approach 1:
The patent applies asymmetry by designing threads with unequal flanks: a long slide flank at a shallow angle (10-20 degrees) that pushes fibers aside without cutting, and a short grip flank that provides holding power. This asymmetric thread geometry eliminates fiber tearing while maintaining penetration capability, directly resolving the contradiction between insertion speed and fiber damage.
Data Source
AI summary
An asymmetric thread impact drivable screw and clip for use with a power impact device for penetrating wood fibers while minimizing cut fibers. The screw includes an impact head and a conical shaped tip having a ballistic insertion angle at the ends of a shank. The shank defines asymmetrical threads with an insertion flank having a long side at a slide angle peaking at a crest supported by a catch flank positioned at a grip angle. Varying tool accepting recess are taught for the head along with multiple thread sections. A mushroom compaction thread section is also taught.