Rotor Unit Clamping Checks During Spindle Acceleration

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Solution Overview

Problem

Existing methods for checking the clamping state of tool holders in machine tools are not easily integratable into the machining process and often require dedicated time periods for measurement, which can lead to inefficiencies and inaccuracies due to factors like chip jamming, causing axial run-out and angular misalignments that affect machining precision.

Innovation Solution

A method utilizing a motor-driven machine tool with a sensor head on the stator unit to measure distance changes relative to the rotor unit, allowing for continuous clamping state checks without time loss, using a marking on the rotor unit for reference and enabling measurements during the acceleration phase, and employing Fourier transformations for error detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a separate time period is provided for testing the clamping state, then measurement accuracy is improved, but productivity decreases due to time loss

Engineering Contradiction:
Improveclamping state detection accuracyVSAvoidmachining process efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The sensor head continuously measures the distance to the rotor unit during the entire acceleration phase without interruption, eliminating the need to stop machining for separate measurement periods. This continuous monitoring approach maintains both high measurement accuracy and production efficiency by integrating the testing function into the normal machining workflow.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The clamping state is tested during the acceleration phase before actual machining begins, allowing any clamping errors to be detected and corrected in advance. This preliminary detection prevents quality issues during production while minimizing time loss since the measurement occurs during the unavoidable acceleration period anyway.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If measurement is performed during acceleration phase, then productivity is improved by eliminating separate measurement time, but measurement precision may worsen due to motion

Engineering Contradiction:
Improvemachining process efficiencyVSAvoiddistance measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The measurement system is specifically designed to operate during the dynamic acceleration phase rather than requiring static conditions. The sensor head tracks the rotor unit's position changes in real-time, and the evaluation unit processes the distance data to detect clamping errors even during motion, making the system adaptive to the dynamic machining environment.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The sensor head provides continuous feedback on the distance to the rotor unit during acceleration, allowing real-time detection of clamping state deviations. This feedback mechanism enables the system to maintain measurement precision by continuously monitoring and comparing distance values against expected ranges, even while the system is in motion.

Inventive Principle:
Principle #23Feedback

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 precise and efficient detection of clamping errors, such as run-out and angular misalignments, during the machining process, reducing downtime and improving machining accuracy by allowing for immediate correction of tool positions and reducing the need for separate sensors.

Implementation Method 1

the sensor measures its distance to the rotor unit

Methodology Applied
Scientific EffectDistance measurement:

Implementation Method 2

Fourier transformations for error detection

Methodology Applied
Scientific EffectFourier transformation:

Data Source

PatentEP3889706B1Method for testing the clamping state during acceleration phase
Publication Date: 2022.05.04 FRANZ KESSLER GMBH
  • EP3889706B1 patent drawingFigure 1~2
  • EP3889706B1 patent drawingFigure 3
  • EP3889706B1 patent drawingFigure 4~5

AI summary

A method is proposed for checking the clamping state of a tool holder or tool clamped in a tool clamping device of a rotor unit (3) of a motor-driven machine tool unit (1), by measuring the distance (u) of the sensor head (5) from a part of the rotor unit (3), with a recording of at least one temporal and/or position-related sequence (20, 21) of the distance values ​​measured with the sensor head (5), wherein, for improved integration of the method, a first and a second temporal and/or position-related sequence are recorded during an acceleration of the rotation of the rotor unit (3) relative to the stator unit (2), in particular when starting up the rotor unit, wherein the temporal and/or position-related information of the sequence vectors of the first and/or second sequence is scaled using the respective associated current velocity (v0).