Variably Threaded Screw Torque Reduction and Debris Containment

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Solution Overview

Problem

Existing screws lack a thread configuration that consistently maintains torque reduction and efficiently contains remnants and debris within the screw hole, particularly when dealing with materials like wood, plastic, and composites, often resulting in over-drilling and debris dispersion.

Innovation Solution

A variably threaded screw design featuring alternating right-hand and left-hand thread pitches, with a helical ridge providing torque reduction and severing capabilities, and maintaining uniform thread diameter and pitch for consistent fastening properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional screw with uniform threading is used, then the screw structure is simple and easy to manufacture, but it cannot effectively reduce torque or contain remnants and debris within the screw hole

Engineering Contradiction:

Improvescrew structure simplicityVSAvoiddebris dispersion and torque

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The screw thread is divided into multiple distinct portions with different characteristics: a first threaded portion with first pitch, a second threaded portion with second pitch, and a third threaded portion with third pitch. This segmentation allows each portion to perform specific functions - the first portion engages the workpiece firmly, the second portion captures remnants, and the third portion provides additional fastening, thereby containing debris and managing torque effectively

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the screw thread are given different local qualities through varying pitch values. The first threaded portion has a pitch optimized for initial engagement, the second threaded portion has a different pitch for capturing remnants, and the third threaded portion has yet another pitch for final fastening. This local differentiation enables the screw to address multiple problems (torque reduction, debris containment) simultaneously

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the screw rotates to insert into the material, then the fastener is driven in, but remnants or slivers are extruded, cutting, or produced and extend from the hole surface

Engineering Contradiction:

Improvescrew insertionVSAvoidremnants and slivers

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The second threaded portion is positioned to engage the workpiece before the screw is fully inserted. As the first threaded portion drives the screw in, the second threaded portion simultaneously engages and begins capturing remnants as they are produced, preventing them from extending from the hole surface before the screw installation is complete

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The rotation that produces harmful remnants is converted into a beneficial process. The second threaded portion, with its distinct pitch, is designed to engage and pull with it the remnants that are extruded during insertion, transforming the harmful effect of material displacement into a useful mechanism for containing and retaining those remnants within the bore

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If a single threaded portion is used, then the screw is simple in structure, but it cannot simultaneously achieve firm engagement and effective remnant containment

Engineering Contradiction:

Improvethread configurationVSAvoidfastening performance and remnant retention

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The single threaded portion is replaced with multiple threaded portions (first, second, and third) that are segmented along the screw shaft. Each segment performs a specific function: the first provides firm engagement, the second captures and retains remnants, and the third provides additional fastening. This segmentation achieves reliable dual functionality without requiring overly complex additional components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-threaded screw design makes the single fastener universal for multiple functions. The first threaded portion handles initial engagement and driving, the second threaded portion handles remnant capture and retention, and the third threaded portion handles final fastening security. This multi-functionality is achieved within a single screw component, maintaining simplicity while enhancing reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8894339B2Variably threaded screw

Publication Date: 2014.11.25 SIMPSON STRONG TIE

AI summary

A variably threaded screw has a first end and a second end, the first end of the shaft terminating in a tip and the second end having a widened head thereon. A first helical thread portion is located on the shaft adjacent the widened head. A second helical thread portion is located on the shaft adjacent the tip of the shaft. A third helical thread portion is located on the shaft between the first helical thread portion and the second helical thread portion. The first helical thread portion and the second helical thread portion have right hand thread pitches. The third helical thread portion has a left hand thread pitch. A helical ridge having a right hand thread pitch intersects the third helical thread portion.