Parallel-Tapered Rebar Coupler for Fast Stable Thread Engagement

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Solution Overview

Problem

Existing screw-coupling technologies for connecting reinforcing bars require multiple turns to engage threads, necessitate alignment of thread start points, and are prone to loosening due to unstable coupling states and axial vibrations.

Innovation Solution

A parallel-tapered-integrated screw-coupling structure that combines a parallel female threaded-portion with a tapered female threaded-portion and a parallel male threaded-portion with a tapered male threaded-portion, allowing for simultaneous engagement of parallel and tapered threads without the need for initial thread alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If only parallel screws are used for coupling, then the coupling is stable and resistant to loosening, but the number of required turning is large and alignment of thread start points is necessary

Engineering Contradiction:

Improvecoupling stabilityVSAvoidcoupling time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The threaded portion is divided into two segments: a tapered threaded portion for initial engagement and guidance, and a parallel threaded portion for stable coupling. This segmentation allows each portion to fulfill its specific function optimally.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tapered threaded portion performs preliminary action by guiding the male screw into proper alignment and initiating engagement before the parallel threaded portion takes over for stable coupling.

Inventive Principle:

Principle #10Preliminary action

2Loss of time

If only tapered screws are used for coupling, then the number of required turning is reduced and guidance is possible, but the coupling state is unstable and loosening occurs under axial flow or vibration

Engineering Contradiction:

Improvecoupling timeVSAvoidcoupling stability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention merges the advantages of both tapered and parallel screw structures into a single integrated threaded portion, combining the guidance capability of tapered screws with the stability of parallel screws.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If tapered screw and parallel screw are simply combined with same maximum major diameter, then the structure is simple, but the female screw and male screw interfere with each other in insertion

Engineering Contradiction:

Improvestructural simplicityVSAvoidinsertion ease

Core Design Contradiction:

Device complexityVSEase of operation

Solution Approach 1:

The threaded portion has different local qualities: the tapered portion has a smaller maximum major diameter than the parallel portion's major diameter, allowing smooth insertion without interference while maintaining structural simplicity.

Inventive Principle:

Principle #3Local quality

4Manufacturing precision

If parallel screw is positioned at end portion further than tapered screw, then the parallel threaded-portion can be formed, but the number of required turning is unavoidably larger and alignment of axes is required

Engineering Contradiction:

Improvethread formation precisionVSAvoidcoupling time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The tapered threaded portion performs preliminary action by guiding the male screw into proper alignment and initiating engagement before the parallel threaded portion takes over for stable coupling.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #1Segmentation

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

This solution reduces the number of turns required for coupling, enhances stability by locking threads without a lock nut, minimizes distortion of straightness, and reduces the likelihood of screw loosening due to axial forces or vibrations.

Implementation Method 1

guidance is possible by the tapered structure when the male threads are inserted

Methodology Applied

Scientific EffectTapered structure guidance: Geometry

Implementation Method 2

simultaneously couples a male-female parallel threaded-portion and a male-female tapered threaded-portion when screw-coupling

Methodology Applied

Scientific EffectThreaded coupling: Screw

Data Source

PatentUS12331776B2Parallel-tapered-integrated screw-coupling structure for connecting reinforcing bars

Publication Date: 2025.06.17 KIM E E

AI summary

In a screw-coupling structure between an internally-threaded body and an externally-threaded body, for connecting reinforcing bars: the internally-threaded body includes, on the inner diameter thereof, a parallel-tapered-integrated internal thread section formed by integrating a parallel internal thread section formed as a parallel screw thread, with a tapered internal thread section formed on one end of the parallel internal thread section so that the minor diameter thereof gradually narrows; and the externally-threaded body comprises, on the outer diameter thereof, a parallel-tapered-integrated external thread section formed by integrating a parallel external thread section formed as a parallel screw thread, with a tapered external thread section formed on one end of the parallel external thread section so that the major diameter thereof gradually narrows.