Centring Sensor Calibration for Pre-Toothed Machine Tools
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Solution Overview
Problem
Existing machine tools for processing pre-toothed workpieces face challenges in accurately calibrating single-centering sensors due to changes in sensor position caused by thermal expansion or movement, leading to inconsistencies in material removal during processing.
Innovation Solution
A machine tool with a calibration device that allows for the precise calibration of the spatial position of a single-centering sensor by using a calibration piece with defined geometries, enabling the sensor to determine its response behavior and maintain consistent positioning relative to the workpiece spindle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the centering sensor is mounted at a distance from the workpiece spindle, then the sensor can be positioned and replaced more easily, but the sensor position changes due to thermal expansion leading to calibration errors
Solution Approach 1:
A calibration device is introduced as an intermediary element between the centering sensor and the workpiece spindle. This calibration device provides a reference surface that enables precise calibration of the sensor's spatial position, compensating for position changes caused by thermal expansion or movement, thus maintaining measurement precision while allowing flexible sensor mounting
Solution Approach 2:
The system performs calibration by determining the spatial position parameters of the centering sensor relative to the workpiece spindle using the calibration device. These positional parameters are then used to calculate and adjust the workpiece measuring position, compensating for thermal expansion and movement effects
2Adaptability or versatility
If the centering sensor is movable relative to the workpiece spindle, then the sensor can be adjusted for different measurements, but reproducible positioning becomes difficult to achieve
Solution Approach 1:
The calibration device serves as a mediator that establishes a reliable reference framework for the movable sensor. By providing a fixed reference surface, it enables reproducible positioning calculations even when the sensor is moved or replaced, maintaining reliability while preserving adaptability
Solution Approach 2:
The system uses the calibration device to determine the actual spatial position of the sensor and provides feedback through calculated workpiece measuring positions. This feedback mechanism compensates for position changes and ensures reproducible measurements regardless of sensor movement or replacement
3Adaptability or versatility
If different centering sensors are used, then sensor replacement is possible, but each sensor has different response behavior requiring individual calibration
Solution Approach 1:
The calibration device acts as a universal intermediary reference that works with any centering sensor. It provides a consistent reference surface that enables standardized calibration procedures, reducing complexity despite sensor variability by establishing a common calibration framework
Solution Approach 2:
The calibration procedure is designed to be self-calibrating using the calibration device as reference. The system automatically determines sensor response behavior and calculates appropriate workpiece measuring positions, reducing manual intervention and procedural complexity while enabling sensor replacement
4Temperature
If the sensor position changes during operation, then thermal expansion effects are present, but accurate centering measurements cannot be maintained
Solution Approach 1:
The system compensates for thermal expansion by dynamically determining and updating the spatial position parameters of the sensor relative to the workpiece spindle. The calibration device provides a stable reference that enables detection and compensation of position changes, maintaining measurement precision despite temperature variations
Solution Approach 2:
The calibration mechanism provides continuous feedback on sensor position relative to the workpiece spindle. This feedback enables real-time compensation for thermal expansion effects by adjusting the workpiece measuring position calculations, maintaining accurate centering measurements throughout operation
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 calibration device ensures reproducible and accurate positioning of the single-centering sensor, leading to consistent material removal and improved processing quality of pre-toothed workpieces.
Implementation Method 1
non-contact centering sensors, operating on an inductive or capacitive basis, to determine the position of the tooth flanks
Implementation Method 2
non-contact centering sensors, operating on an inductive or capacitive basis, to determine the position of the tooth flanks
Data Source
Figure 1a~1b
Figure 2a~2d
Figure 2e~2h
AI summary
A machine tool for machining workpieces with precut teeth has a workpiece carrier (20), a workpiece spindle (21) with a workpiece spindle housing (211) and a workpiece spindle shaft (212) which can be rotated about a workpiece spindle axis (A). Furthermore, the machine tool has a centring sensor (1) which is designed to determine a phase position of teeth of a workpiece (23) rotating about the workpiece spindle axis (A), a calibrating piece (10) which is situated at a defined calibrating location (CM) relative to the workpiece spindle (21), and a sensor controller which is designed to carry out the following method: moving the centring sensor (1) relative to the workpiece spindle (21) into a calibrating position in which the centring sensor (1) is situated at the calibrating piece (10); determining a response behaviour of the centring sensor (1) in that the sensor controller (3) moves the centring sensor (1) relative to the calibrating piece (10) and in so doing receives sensor-calibrating signals from the centring sensor (1), and moving the centring sensor (1) into a workpiece-measuring position (PW) in which the centring sensor (1) is situated at the workpiece, wherein the workpiece-measuring position depends on the determined response behaviour.