Threaded Rebar Coupler Structure Without Diameter Enlargement
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Solution Overview
Problem
Existing threaded reinforcing bar couplings for deformed reinforcing bars in reinforced concrete face challenges such as decreased proof stress due to male threaded portion processing, increased manufacturing costs, and lower productivity in mass production, particularly due to the need for large diameter portion formation and adjustments in pitch during roll forming.
Innovation Solution
A threaded reinforcing bar coupling structure featuring a pair of reinforcing bars with a screw tubular coupler, where at least one reinforcing bar has a male threaded portion with a larger thread ridge diameter and smaller thread groove diameter than the main body, formed by rolling without preprocessing, allowing for connection without diameter enlargement and simplifying bar arrangement and construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a male threaded portion is formed on a reinforcing bar by cutting, then the threaded portion can be created, but proof stress or strength decreases due to partial loss of cross-section
Solution Approach 1:
The patent changes the formation method from cutting to rolling, and further optimizes by controlling the thread ridge diameter to be larger than the base diameter. This parameter change allows the threaded portion to gain strength through work hardening during rolling, compensating for the cross-sectional area reduction and achieving proof stress equal to or greater than the base portion.
2Strength
If a large diameter portion is provided on the reinforcing bar to roll a male thread, then proof stress is maintained, but manufacturing costs increase
Solution Approach 1:
The patent eliminates the need for large diameter portions by changing the thread formation parameters. By rolling threads directly on the base diameter portion and controlling the thread ridge diameter to be larger than the base diameter, the invention achieves sufficient proof stress without the additional cost of creating large diameter portions.
3Ease of manufacture
If roll forming is used to create large diameter portions, then manufacturing is simplified, but pitch errors occur requiring position adjustment
Solution Approach 1:
The patent extracts and eliminates the large diameter portion formation step entirely from the manufacturing process. By rolling threads directly on the base diameter portion with controlled thread ridge diameter, the invention removes the source of pitch errors and the subsequent position adjustment requirements, simplifying the manufacturing process while maintaining precision.
4Ease of manufacture
If the thread groove diameter is smaller than the reinforcing bar main body diameter, then the threaded portion can be formed, but cross-sectional area decreases
Solution Approach 1:
The patent changes the critical parameter of thread ridge diameter to be larger than the base diameter, which compensates for the cross-sectional area reduction caused by the smaller thread groove diameter. The work hardening effect during rolling further increases the strength, ensuring that the threaded portion achieves proof stress equal to or greater than the base portion despite the reduced cross-sectional area.
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 configuration maintains sufficient proof stress by compensating for the decrease in thread groove diameter with increased hardness from work hardening, reduces manufacturing costs, and enhances productivity by eliminating the need for large-scale preprocessing and grout filling, while allowing for adjustable lengths and simplified construction processes.
Implementation Method 1
the male threaded portion has hardness or tensile strength greater than that of a remaining portion of the reinforcing bar
Data Source
AI summary
A threaded reinforcing bar coupling structure comprises a pair of reinforcing bars and a tubular coupler connecting the pair of reinforcing bars. Each of the reinforcing bars is a deformed reinforcing bar having spiral node portions on an outer periphery of a reinforcing bar main body having a round shaft shape. A cylindrical portion with node portions removed is formed on an end portion of the reinforcing bar, and a male threaded portion is formed on the cylindrical portion. The male threaded portion has hardness or tensile strength greater than that of a remaining portion of the reinforcing bar. The pair of reinforcing bars is connected by the screw tubular coupler that is screwed onto the male threaded portions.