Tool Approach Detection Using Coolant-Induced Shaft Displacement
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Solution Overview
Problem
Existing machining processes in CNC machines require time-consuming tool exchange for probing the workpiece position, leading to inefficiencies due to large tolerances and varying dimensions of workpieces.
Innovation Solution
A device and method utilizing a measurement arrangement with a measuring graduation and position sensors on a shaft, coupled with a data processor, to determine the approach of a tool to a workpiece by analyzing coolant-induced shaft displacements, allowing for precise positioning without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a probe is used to determine workpiece position, then measurement precision is improved, but productivity deteriorates due to time-consuming tool exchange
Solution Approach 1:
The patent combines the probing function with the coolant supply system by integrating a flow sensor into the coolant channel. This allows the tool to simultaneously perform machining and workpiece position detection without requiring separate probe tools, thereby eliminating tool exchange time while maintaining measurement capability
Solution Approach 2:
The tool is designed with multi-functionality by incorporating both cutting edges for machining and a coolant channel with flow sensor for position detection. This universal design allows the same tool to perform multiple functions (material removal and position measurement) without requiring separate specialized tools
2Manufacturing precision
If a probe is used to measure workpiece dimensions, then manufacturing precision is improved, but loss of time increases due to separate probing steps
Solution Approach 1:
The patent enables continuous position detection by integrating the flow sensor into the coolant system that operates throughout the machining process. The workpiece position can be determined continuously during machining rather than requiring separate probing steps, maintaining manufacturing precision while eliminating time loss
3Temperature
If coolant flow is increased to improve cooling, then temperature control is improved, but shaft displacement increases affecting measurement accuracy
Solution Approach 1:
The patent employs feedback by using the flow sensor to detect coolant flow changes caused by shaft displacement. This feedback mechanism allows the system to monitor and compensate for displacement effects, enabling accurate position measurement even when coolant flow varies for cooling purposes
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
Enables rapid and accurate determination of workpiece position, reducing setup time and enhancing machining efficiency by eliminating the need for separate probing steps.
Implementation Method 1
a measurement arrangement having a measuring graduation arranged in a rotationally fixed manner on the shaft and at least one position sensor arranged in a fixed manner relative to the shaft, and a data processor... The position sensor is adapted to scan the measuring graduation and to generate position values therefrom that indicate a position of the shaft
Implementation Method 2
by evaluating a progression of the position values when the tool approaches the workpiece, determines that the tool is located in an approach area relative to the workpiece, in which a displacement of the shaft occurs resulting from the dynamic pressure of the coolant flow impinging on the workpiece
Data Source
AI summary
A device for determining an approach of a tool to a workpiece in a machine tool with internal cooling supply includes a measuring arrangement, having a measuring graduation arranged in a rotationally fixed manner on a shaft and at least one position sensor arranged in a fixed manner relative to the shaft, and a data processor. The position sensor is adapted to scan the measuring graduation and to generate position values therefrom that indicate a position of the shaft. The position values are fed to the data processor, which, by evaluating a progression of the position values when the tool approaches the workpiece, determines that the tool is located in an approach area relative to the workpiece, and signals, by an approach signal, when the tool reaches an approach position relative to the workpiece, in which the tool is close to the workpiece without touching it.