Oscillating Tool Machining for Lower Thrust Force at High Feed
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Solution Overview
Problem
Machining operations, such as drilling, face challenges in balancing speed with thrust force and torque, as rapid operations can shorten tool life and affect the geometry and integrity of the workpiece, particularly due to excessive force application.
Innovation Solution
A method involving linear movement of a tool along a feed axis with superimposed oscillation and rotation, where the optimal oscillation frequency is determined to minimize force application during machining, allowing for controlled thrust force management and extended tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If machining operations are performed quickly to increase productivity, then productivity is improved, but thrust force and torque increase which shortens tool life and affects workpiece integrity
Solution Approach 1:
The patent applies ultrasonic vibration to the cutting tool, causing it to oscillate at high frequency during the machining operation. This vibration reduces the average cutting force and torque between tool and workpiece, enabling faster feed rates without exceeding maximum force thresholds that would damage the tool or workpiece. The vibratory motion creates periods of reduced contact pressure, effectively lowering the mean thrust force while maintaining high productivity.
Solution Approach 2:
The machining process utilizes periodic ultrasonic vibrations superimposed on the continuous feed motion. The tool alternates between high-contact-force phases and low-contact-force phases during each vibration cycle, creating a periodic action pattern. This periodic variation in contact force allows the average force to remain below damaging thresholds while the cumulative material removal rate increases, resolving the contradiction between speed and tool life.
2Productivity
If machining operations are performed quickly to increase productivity, then productivity is improved, but thrust force and torque increase which affects the geometry and integrity of the workpiece feature
Solution Approach 1:
Ultrasonic vibration of the tool reduces the average cutting forces during machining, preventing excessive thrust forces that would cause workpiece deformation, vibration, or geometric errors. The high-frequency oscillations create a more stable cutting process with reduced mean forces, enabling faster feed rates while maintaining dimensional accuracy and feature integrity.
Solution Approach 2:
The patent changes the physical state and motion parameters of the cutting tool by superimposing ultrasonic vibration frequencies (typically 20-100 kHz) on the feed motion. This parameter change transforms the cutting process from continuous high-force contact to periodic low-average-force contact, allowing high productivity while maintaining manufacturing precision through reduced force-induced deformations.
3Reliability
If oscillation is superimposed at multiple frequencies during optimization mode, then the optimal frequency minimizing force is determined, but the process time increases
Solution Approach 1:
The patent performs a preliminary optimization phase where multiple oscillation frequencies are tested to identify the optimal frequency that minimizes cutting forces for specific workpiece materials and conditions. This preliminary action establishes a database of optimal parameters that can be stored and reused for subsequent machining operations on similar materials, eliminating the need to repeat the time-consuming frequency sweep for every workpiece.
Solution Approach 2:
The optimization results obtained from testing multiple frequencies on representative workpiece samples are copied and stored as reference data. When machining similar materials, the pre-determined optimal frequency is applied directly without repeating the full frequency sweep, significantly reducing the time loss while maintaining force control optimization.
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 enables faster machining velocities while maintaining control over thrust force, prolonging tool life and enhancing the quality of the machined features by reducing force-related damage.
Implementation Method 1
providing linear movement of a tool along a feed axis relative to a workpiece... provided by a linear motor
Implementation Method 2
superimposing oscillation of the tool onto the feed axis... the oscillation frequency that causes the tool to apply less force to the first workpiece portion
Data Source
AI summary
An example method includes performing a machining operation by providing linear movement of a tool along a feed axis relative to a workpiece while superimposing oscillation of the tool onto the feed axis and providing rotation of the tool relative to the workpiece. During an optimization mode, the machining operation is performed on a first workpiece portion while providing the linear movement at an initial feed velocity, and sequentially superimposing the oscillating at a plurality of different frequencies. An optimal oscillation frequency is determined from the plurality of different frequencies which causes the tool to apply less force to the first workpiece portion at the initial feed velocity than others of the frequencies. During a run mode, the machining operation is performed on a second workpiece portion having a same composition as the first workpiece portion while superimposing the oscillation at the optimal oscillation frequency.