Variable Thread Fastener Reduces Installation Torque

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Solution Overview

Problem

Conventional fasteners face challenges in securely binding materials with varying materials, such as wood and composites, often requiring high torque for installation and not efficiently utilizing the material's surface for secure embedding.

Innovation Solution

A fastener design featuring a shank with a blunt leading end and a contiguous helical thread having varying thread angles and serrated edges, combined with knurls, which reduces the torque required for installation and enhances material engagement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional fasteners are used to bind materials, then the fastener can secure materials together, but high torque is required for installation

Engineering Contradiction:

Improvematerial binding strengthVSAvoidinstallation torque

Core Design Contradiction:

StrengthVSEase of operation

Solution Approach 1:

The thread structure transitions from symmetric to asymmetric configuration along the shank length. The forward-facing asymmetric thread portion (closer to tip) has different geometric properties than the rearward-facing symmetric thread portion, optimizing engagement at different installation stages to reduce required torque while maintaining binding strength

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The thread geometry dynamically changes along the length of the shank, transitioning from symmetric to asymmetric configuration. This dynamic variation in thread structure allows the fastener to adapt its engagement characteristics during installation, reducing peak torque requirements compared to uniform symmetric threads

Inventive Principle:

Principle #15Dynamics

2Strength

If conventional fasteners are used to bind materials, then the fastener can secure materials together, but the material surface is not efficiently utilized for secure embedding

Engineering Contradiction:

Improvematerial binding strengthVSAvoidmaterial surface utilization

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The asymmetric thread portion is specifically positioned to engage with the forward-facing material surface, optimizing the utilization of available material area for secure embedding while the symmetric portion handles rearward engagement

Inventive Principle:

Principle #3Local quality

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 fastener design significantly reduces installation torque and improves material binding by utilizing serrated edges and knurls, providing enhanced performance in securing elements in wood and composite materials.

Implementation Method 1

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9523383B2Variable thread fastener

Publication Date: 2016.12.20 SIMPSON STRONG TIE

AI summary

A fastener includes a shank having a first end and a second end. A first portion of a thread is formed with a first, symmetric thread angle and a second portion of the thread is formed with a second, asymmetric thread angle. The thread may be serrated or jagged over one or more portions of the fastener, including the area of the symmetric thread angle. A blunt end comprises the leading end of the fastener.