Rebar Coupler With Fine-Thread Plug to Prevent Slippage
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Solution Overview
Problem
Existing couplers for threaded reinforcing bars in concrete construction suffer from slippage due to loose tolerances and inability to install in situations where rotation is restricted or a gap needs to be bridged.
Innovation Solution
A coupler design featuring a first fitting with a coarse internal thread and a finer secondary internal thread, along with a plug that applies a preload by threading into the finer thread, ensuring secure engagement even with coarse threaded reinforcing bars.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cast construction fitting with sand core internal thread is used for cost considerations, then manufacturing cost is reduced, but thread engagement precision deteriorates causing slippage under high loads
Solution Approach 1:
The fitting incorporates two different internal threads with different pitch qualities: a coarse first internal thread for initial engagement and cost-effective manufacturing, and a fine second internal thread for precise engagement and preventing slippage. This local differentiation of thread quality resolves the contradiction between manufacturing cost and engagement precision.
2Reliability
If epoxy cement is used to fill the coupler interior to avoid slippage, then slippage control is improved, but installation time and cost increase
Solution Approach 1:
The invention replaces the chemical/effective solution of epoxy cement filling with a mechanical solution: a plug threaded into a fine pitch internal thread that mechanically prevents slippage. This substitution eliminates the need for epoxy application and curing time, resolving the contradiction between slippage control and installation efficiency.
3Manufacturing precision
If machining metric threads or swaging sleeves is performed on threaded reinforcing bar ends, then coupling precision is improved, but installation complexity and cost increase
Solution Approach 1:
The fitting is segmented into two distinct threaded portions: a first internal thread matching the reinforcing bar and a second internal thread for the plug. This segmentation allows the fitting itself to provide the precision engagement mechanism without requiring additional machining or swaging operations on the reinforcing bar, thus improving coupling precision while maintaining installation simplicity.
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 coupler effectively minimizes slippage and allows for secure coupling of threaded reinforcing bars, even in situations where rotation is restricted or a gap needs to be bridged, while reducing installation torque and costs.
Implementation Method 1
a plug for threading into the second internal thread for abutting an end of said threaded reinforcing bar
Implementation Method 2
The plug is configured for being tightened in said second internal thread for applying a preload against said end of said threaded reinforcing bar
Implementation Method 3
the engagement formation is frangibly connected to a remainder of the plug
Data Source
AI summary
A coupler including a first fitting for mounting to a first externally threaded reinforcing bar for use in concrete construction, the first fitting comprising a first body having a first internal thread for threadedly inserting the first externally threaded reinforcing bar into the first fitting; the first fitting having a second internal thread having a pitch finer than a pitch of the first internal thread; and a plug for threading into the second internal thread for abutting an end of said threaded reinforcing bar.