Hybrid Threading Tap With Residual-Stress Hole Expansion
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Solution Overview
Problem
Current methods for manufacturing threaded holes are suboptimal, leading to limited performance in terms of fatigue resistance and load retention strength, especially in high-volume manufacturing processes, and are often inefficient.
Innovation Solution
A hybrid threading tap with a reamer portion and a thread cutting portion, where the reamer portion plastically deforms and expands the hole to create a zone of residual compressive stress, and the thread cutting portion cuts the threading into this expanded zone, providing high fatigue resistance and load retention strength, while also improving manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional threading tools and methods are used, then manufacturing processes are simpler, but the threaded holes have limited fatigue resistance and load retention strength
Solution Approach 1:
The patent combines the reamer portion and thread cutting portion into a single hybrid threading tap tool. The reamer portion plastically deforms and expands the hole to create residual compressive stress, while the thread cutting portion cuts threads into the expanded hole in sequence during one continuous operation. This merging of two separate operations (reaming and threading) into one tool resolves the contradiction by enabling high-strength threaded holes without requiring multiple tools or operations, thus maintaining manufacturing simplicity while achieving superior fatigue resistance and load retention strength.
Solution Approach 2:
The reamer portion performs preliminary action by plastically deforming and expanding the hole before the thread cutting portion creates the threads. This preliminary expansion creates a zone of residual compressive stress in the hole wall, which preconditions the material to enhance fatigue resistance and load retention strength before the actual threading operation occurs. This sequential preliminary action resolves the contradiction by preparing the hole structure in advance to achieve high strength properties.
2Productivity
If multiple separate operations (drilling, reaming, threading) are used, then each operation can be optimized independently, but manufacturing efficiency decreases and time increases
Solution Approach 1:
The patent merges reaming and threading operations into a single hybrid threading tap that performs both functions in one continuous stroke. The reamer portion and thread cutting portion are arranged sequentially along the tool axis, allowing the tool to first expand the hole and then cut threads without removing the tool from the workpiece. This combining of operations eliminates the time losses associated with multiple separate operations, directly improving manufacturing efficiency and reducing total production time.
Solution Approach 2:
The hybrid threading tap maintains continuous useful action by performing reaming and threading in one uninterrupted sequence during a single stroke. The reamer portion continuously expands the hole while the thread cutting portion continuously cuts threads as the tool advances, without idle time between operations. This continuity eliminates the start-stop cycles and tool changes inherent in multiple separate operations, thereby maximizing productivity and minimizing time loss.
3Manufacturing precision
If conventional threading methods are used, then manufacturing processes are simpler, but the quality and performance of threaded holes are limited
Solution Approach 1:
The patent merges the reamer portion and thread cutting portion into one integrated hybrid threading tap tool. The reamer portion plastically deforms the hole material to create residual compressive stress, and the thread cutting portion cuts precise threads into the expanded hole. This merging enables high manufacturing precision in terms of thread quality and hole strength without requiring multiple separate tools, thus achieving high-quality threaded holes while keeping the device structure relatively simple.
Solution Approach 2:
The hybrid threading tap applies local quality by creating a zone of residual compressive stress specifically in the hole wall through the reamer portion's plastic deformation. This localized stress zone enhances fatigue resistance and load retention strength precisely where the threads will be cut and where stress concentrations occur. The local quality improvement in the hole structure enables high manufacturing precision for thread performance without requiring complex tooling throughout the entire manufacturing system.
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 hybrid threading tap enhances the quality of threaded holes by providing high fatigue resistance and load retention strength, while increasing manufacturing efficiency by allowing for high-quality threaded holes to be created in a single stroke, suitable for various parts including engine blocks.
Implementation Method 1
The reamer portion is configured to be advanced within a hole of a workpiece to plastically deform and expand the hole to an expanded hole and provide the expanded hole with a zone of residual compressive stress
Implementation Method 2
The plurality of cutting teeth is configured to cut a threading into the expanded hole within the zone
Data Source
AI summary
A hybrid threading tap includes a reamer portion and a thread cutting portion having a plurality of cutting teeth. The thread cutting portion is arranged with the reamer portion along the longitudinal axis. The reamer portion is configured to be advanced within a hole of a workpiece to plastically deform and expand the hole to an expanded hole and provide the expanded hole with a zone of residual compressive stress. The plurality of cutting teeth is configured to cut a threading into the expanded hole within the zone.