RF Time-of-Flight Tool Inspection in Machine Tool Holders
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Solution Overview
Problem
Current tool inspection methods for machine tools, such as cutting machining tools, face challenges including increased cycle time and reduced measurement accuracy due to the need for separate measurement stations and interference from contaminants like chip deposits and coolants in optical inspection systems, which are not effectively addressed by existing solutions like light grids or energy consumption analysis.
Innovation Solution
A sensor utilizing the time domain reflectometry (TDR) principle, which transmits and receives radio frequency signals to measure the time of flight along the tool, allowing for in-situ inspection without a separate measurement station, and is robust against environmental interference, enabling continuous monitoring during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensors are used for tool inspection, then tool defects can be detected, but the cycle time increases due to travel to separate measurement station
Solution Approach 1:
The patent combines the measurement function directly into the tool holder, merging the inspection capability with the tool mounting structure. This eliminates the need for separate measurement stations and travel time, allowing inspection to occur in-situ during normal operation.
Solution Approach 2:
The tool holder performs self-inspection by measuring its own dimensional changes through integrated sensors that detect thermal expansion and mechanical deformation directly at the tool mounting location, without requiring external measurement equipment or intervention.
2Measurement precision
If optical sensors are used for tool inspection, then tool defects can be detected, but the measurement accuracy is reduced due to environmental interference
Solution Approach 1:
The patent replaces optical sensing with mechanical sensing by integrating strain gauges and displacement sensors directly into the tool holder. These mechanical sensors are immune to environmental interference such as chip deposits, coolant mist, and lighting conditions that plague optical systems.
Solution Approach 2:
The tool holder itself acts as an intermediary between the tool and the measurement system, with integrated sensors that directly contact and measure the tool's physical state. This intermediary structure protects the measurement process from environmental contaminants while maintaining measurement accuracy.
3Measurement precision
If a separate measurement station is used for tool inspection, then tool defects can be detected, but the space requirement increases within the machining area
Solution Approach 1:
The measurement function is merged into the tool holder structure itself, eliminating the need for separate measurement stations. The tool holder becomes both the mounting structure and the measurement device, consolidating functions and freeing up machining space.
Solution Approach 2:
The tool holder is designed with multi-functionality, serving both as the mechanical mounting structure for the tool and as the measurement system. This universal design eliminates dedicated measurement equipment and maximizes the useful machining space.
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 significantly reduces cycle time and improves measurement accuracy by allowing tool inspection during regular operation, providing reliable length information and defect detection without the need for additional space or separate measurement stations, and can assess tool condition and correct clamping.
Implementation Method 1
measuring a time of flight of the radio frequency signal in the tool
Implementation Method 2
A further conventional field of use is the determination of filling levels. The TDR principle is based on the determination of times of flight of an electromagnetic pulse for the determination of the distance of a discontinuity
Data Source
AI summary
A sensor (10) for inspecting a tool (28) of a machine tool (24) is provided that has a radio frequency transmitter (12) for generating a radio frequency signal, a radio frequency receiver (14) for generating a received signal from a received radio frequency signal, a coupling unit (16) to couple a radio frequency signal into the tool (28) and to decouple it from the tool (28), and a control and evaluation unit (20) to determine a time of flight of a radio frequency signal transmitted from the radio frequency transmitter (12) and received again by the radio frequency receiver (14) with reference to the received signal of the radio frequency receiver (14).