Roto Peening Orbital Drilling Tool for Single-Pass Fatigue Improvement
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Solution Overview
Problem
Conventional drilling processes are time-consuming and may compromise material fatigue properties, particularly in aluminum and titanium, and lack efficient methods for inducing residual stress in a single pass, necessitating secondary peening operations.
Innovation Solution
A machining tool with a shaft and cutting portion integrated with a residual stress inducer featuring a torsion element and carbide tip, which extends to contact the workpiece surface at altered rotational speeds to induce compressive residual stress during the machining process, allowing for improved fatigue properties in a single pass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional drilling processes are used, then holes can be generated in materials, but the process is time-consuming and requires secondary peening operations
Solution Approach 1:
The patent combines the cutting function and peening function into a single integrated tool. The cutting portion creates the hole while the residual stress inducer with carbide tips performs peening on the hole surface simultaneously, eliminating the need for separate peening operations and reducing cycle time
Solution Approach 2:
The peening action continues throughout the hole formation process. As the cutting portion progresses through the material, the carbide tips continuously impact the hole surface to induce compressive residual stress, ensuring the entire hole surface is treated without interruption
2Strength
If drill/ream process is used, then fatigue life in aluminum is improved, but coolant usage increases and burrs are produced
Solution Approach 1:
The peening process is self-contained and does not require external coolant systems. The mechanical impact of the carbide tips on the hole surface creates the desired compressive residual stress without generating excessive heat or requiring large amounts of coolant for cooling and lubrication
3Ease of manufacture
If a separate peening device is used, then surface preparation can be performed, but the process requires tool changeovers
Solution Approach 1:
The cutting portion and residual stress inducer are integrated into a single tool assembly that can be installed in the machine tool once. This eliminates the need for tool changeovers between cutting and peening operations, simplifying the manufacturing process and reducing setup time
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 solution enables the creation of holes with enhanced fatigue properties in aluminum and titanium by integrating a peening mechanism into the cutting tool, eliminating the need for secondary processes and improving machining efficiency.
Implementation Method 1
The rotational speed is then altered to extend the torsion elements to allow contact with the surface of the workpiece by a carbide tip on the torsion element
Data Source
AI summary
A machining tool incorporates a shaft having a first end configured to fit into a machining collet. A cutting portion extends from a second end of the shaft. A residual stress inducer is located between the first and second ends and includes a torsion element joined to the shaft at a connection end. A carbide tip is present on a free end opposite the connection end and the torsion element is configured such that a selected rotational speed, altered from a normal cutting speed, causes the carbide tip of the torsion element to contact a workpiece surface.