Hot-Rolled Threaded Rebar Bolt With Smooth Shaft
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Solution Overview
Problem
Current methods for manufacturing large quantities of threaded rebar bolts for mine roof support and other structural applications are costly and inefficient, as they require slow and expensive processes like cold-cutting and cold-forming, and existing bolts with longitudinal ribs are not suitable for re-tensioning and rotation in grouted structures.
Innovation Solution
The development of hot-rolled threaded rebar bolts with semi-continuous threads and no longitudinal ribs, produced through a continuous hot-rolling process, allowing for high-volume, cost-effective manufacturing and enabling re-tensioning without additional hardware or machining steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cold-cutting or cold-forming processes are used to manufacture threaded rebar bolts, then manufacturing precision and thread quality are improved, but production speed decreases and manufacturing cost increases
Solution Approach 1:
The patent changes the temperature parameter from cold to hot during the threading process. By heating the rebar to austenite temperature range and then rapidly cooling it, the steel's mechanical properties change, allowing threads to be formed with superior quality while enabling continuous high-speed production through the rolling process.
Solution Approach 2:
The patent replaces the mechanical cutting or forming processes with a thermal-mechanical process. Instead of using cutting tools or cold-forming dies, the invention uses controlled heating and rapid cooling to create threads through phase transformation, eliminating the need for slow sequential cutting operations.
2Manufacturing precision
If cold-cutting or cold-forming processes are used to manufacture threaded rebar bolts, then thread quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent implements a continuous hot-rolling threading process where rebars move continuously through heating zones and rolling dies without stopping or sequential operations. This continuous action eliminates the need for multiple setup changes, tool changes, and intermittent operations, dramatically reducing manufacturing cost while maintaining high thread quality.
Solution Approach 2:
By changing from cold to hot processing parameters, the invention enables a fundamentally different manufacturing approach that is both faster and cheaper. The hot-rolling process allows for continuous production with fewer interruptions, lower tooling costs, and reduced energy consumption compared to cold-cutting methods.
3Strength
If longitudinal ribs are present on hot-rolled rebar, then rebar strength is improved, but the ability to rotate and tension bolts is lost
Solution Approach 1:
The patent segments the rebar surface into two distinct zones: a threaded portion that is smooth and rotation-capable, and a non-threaded portion that retains longitudinal ribs for anchorage. This segmentation allows the bolt to rotate and tension in the smooth zone while the ribbed zone provides grip in the grout, resolving the contradiction between rotation capability and anchorage strength.
Solution Approach 2:
The invention applies different surface qualities to different portions of the rebar. The threaded portion has a smooth, rotation-friendly surface, while the anchorage portion maintains rough longitudinal ribs. This local differentiation allows each zone to perform its specific function optimally without compromising the other.
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 approach reduces material and labor costs, improves bolt performance by allowing re-tensioning, and eliminates the need for additional hardware, while maintaining structural integrity and enabling efficient production of large quantities of bolts.
Implementation Method 1
The invention provides hot-rolled threaded rebar bolts that are cheaper to manufacture but maintain the same or similar structural benefits of more costly manufactured bolts
Data Source
AI summary
Embodiments of the present invention include hot-rolled threaded rebar bolts that have a substantially circular core with semi-continuous threads on opposing sides of the rebar bolts. In some embodiments of the invention the shaft is substantially void of longitudinal ribs along at least a portion of the longitudinal area between the first set of threads and the second set of threads of the shaft. The threaded rebar bolt is manufactured in a continuous hot-rolling process to create a threaded rebar shaft with semi-continuous threads and substantially no longitudinal ribs in the longitudinal areas and no additional machining is required to create the threads after the threaded shaft is created from the hot-rolling process.