Ultrasonic Tool Holder Sensing for Adaptive CNC Machining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing machining methods face challenges in accurately detecting material changes during ultrasonic machining due to external vibration interference, leading to incorrect adjustment of processing parameters, especially in composite materials with varying layer thicknesses and irregularities.
Innovation Solution
An ultrasonic generator integrated into the tool holder serves as both a vibration source and sensor, allowing for precise detection of resonant frequency and damping capacity close to the workpiece, minimizing external vibration influence and enabling accurate material change identification and parameter adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a structure-borne sound sensor is attached to the machine frame at a considerable distance from the workpiece to detect material changes, then the sensor can detect vibrations, but external vibrations from the environment superimpose on the measurement signal, leading to incorrect evaluation and adjustment of machining parameters
Solution Approach 1:
The measurement function is extracted from the distant machine frame and relocated to the tool holder, which is positioned close to the workpiece. This extraction removes the measurement system from the environment where external vibrations occur, thereby eliminating the harmful superposition of external vibrations on the measurement signal.
Solution Approach 2:
The tool holder acts as an intermediary between the ultrasonic generator and the workpiece, and simultaneously serves as the mounting position for the measurement sensor. This intermediary position allows the sensor to detect vibrations directly at the source of material changes while being isolated from external environmental vibrations that affect distant machine frame sensors.
2Adaptability or versatility
If the ultrasonic generator is used solely for generating vibrations, then the system is simple, but material changes during machining cannot be detected for adaptive parameter adjustment
Solution Approach 1:
The ultrasonic generator is designed to perform dual functions: generating ultrasonic vibrations for machining and simultaneously serving as a measurement sensor for detecting material changes. This multi-functionality allows the system to adapt machining parameters based on real-time material condition detection without adding separate measurement devices, thereby maintaining system simplicity while enhancing adaptability.
Solution Approach 2:
The measurement sensor is merged with the ultrasonic generator by mounting it on the tool holder at the same location. This combination integrates the vibration generation and measurement functions into a single coordinated system, enabling simultaneous execution of both functions without increasing overall system complexity.
3Manufacturing precision
If machining parameters are adjusted based on incorrect evaluation of vibration signals, then parameter adaptation is attempted, but the adjustment is wrong leading to suboptimal machining quality
Solution Approach 1:
The mechanical vibration detection system is replaced with an electrical measurement system. The measurement sensor converts mechanical vibrations into electrical signals that can be processed and evaluated electronically, providing more accurate and reliable detection of material changes compared to mechanical detection methods, thereby preventing incorrect parameter adjustments.
4Productivity
If the tool is moved quickly through the workpiece to reduce processing time, then productivity increases, but material changes cannot be detected in real-time for parameter adjustment
Solution Approach 1:
The measurement sensor continuously monitors vibrations during the entire machining process without interruption. This continuous detection enables real-time identification of material changes, allowing immediate parameter adjustments to be made while machining continues, thereby maintaining high productivity without sacrificing detection accuracy or requiring time-consuming parameter changes.
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 allows for pinpoint detection of material changes and adaptive processing parameters, reducing processing time and ensuring optimal machining conditions for diverse materials, including composite materials like CFRP and ceramics, by distinguishing material changes from other frequency shifts such as those caused by heating.
Implementation Method 1
generating an ultrasonic vibration of the tool by means of an ultrasonic generator
Implementation Method 2
the largest possible mechanical vibration amplitude is obtained when the vibrating system is excited with its resonant frequency
Implementation Method 3
When the tool enters the workpiece, the vibrating system is damped by the workpiece material and the friction between the workpiece and the tool, and the resonant frequency shifts to a slightly lower frequency
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The inventive method for machining a workpiece (WS) on a numerically controlled machine tool using a tool (90) comprises the steps: controlling a relative movement of the tool relative to the workpiece for machining the workpiece, generating an ultrasonic vibration of the tool by means of an ultrasonic generator, detecting at least one sensor signal output from the ultrasonic generator, and detecting a change in the material of the workpiece during the control of the relative movement of the tool relative to the workpiece (WS) based on the at least one sensor signal output from the ultrasonic generator.