Spindle Head Load Mapping for Condition-Based Machine Tool Maintenance
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Solution Overview
Problem
Conventional methods for determining when to replace moving parts of a machine tool are inefficient, often leading to premature replacement or failure to detect precision deviations within specified tolerances, due to cycle-based replacement strategies and complex spot checks.
Innovation Solution
A device that records the position of the spindle head relative to a fixed point during operation, generates virtual measurements through interpolation, and determines load values based on position frequency, time, speed, acceleration, and mechanical load, allowing for precise identification of highly loaded positions and reduced maintenance expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cycle-based replacement of moving parts is used, then maintenance is simplified and performed regularly, but parts are replaced prematurely even when the machine tool is still producing within specified tolerances
Solution Approach 1:
The system continuously monitors the actual machining precision through measuring units and feeds this information back to the control unit. The control unit compares measured values against tolerance specifications and dynamically adjusts maintenance scheduling based on actual performance degradation, replacing parts only when precision deviations exceed acceptable thresholds rather than following fixed cycles.
Solution Approach 2:
The maintenance schedule transitions from a static, predetermined cycle-based approach to a dynamic, condition-based approach. The system adapts maintenance timing based on real-time monitoring of machining precision, wear indicators, and operational conditions, allowing maintenance intervals to extend or contract based on actual part condition and performance.
2Measurement precision
If spot checks of manufactured workpieces are performed with high precision, then machining accuracy within tolerances is accurately verified, but the checking process becomes very complex
Solution Approach 1:
The system extracts critical measurement parameters from complex workpiece inspections and focuses monitoring on specific key features that indicate overall machining precision. Rather than performing comprehensive high-precision checks on entire workpieces, the system identifies and monitors critical dimensions and tolerances that serve as proxies for overall quality, simplifying the checking process while maintaining verification accuracy.
Solution Approach 2:
The system replaces complex mechanical measurement and inspection processes with automated sensor-based monitoring and computational analysis. Measuring units with sensors continuously track position, velocity, acceleration, and other parameters, using electronic data processing and control algorithms to assess precision rather than manual measurement methods.
3Measurement precision
If measured values are recorded at frequent intervals, then detailed position data is captured for accurate load determination, but the quantity of data to be processed and stored increases significantly
Solution Approach 1:
The system records measured values at intervals that are sufficient to capture essential load patterns and position changes without excessive granularity. Rather than continuous recording, the system uses strategically selected time and position intervals that provide adequate resolution for load determination while keeping data volumes manageable for processing and storage.
Solution Approach 2:
The control unit applies preliminary processing and filtering to measured values as they are collected, identifying and eliminating redundant or outlier data points before full analysis. The system pre-processes data streams to consolidate information, aggregate readings, and remove duplicates, reducing the volume of data requiring detailed analysis while preserving essential measurement information.
Data Source
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AI summary
Device (10) for determining highly loaded positions (50) in a machine tool (12) with a spindle unit (14) having a spindle head (16) and a spindle motor (18), the device (10) comprising a measuring unit (30) configured to acquire measured values (32) for the spindle head (16) during operation of the spindle unit (14), wherein the measured values (32) represent a current position (50) of the spindle head (16) relative to a fixed point (FP) of the machine tool (12); a storage unit (34) configured to store the measured values (32) acquired by the measuring unit (30); a load determination unit (36) configured to determine an associated load value (52) for each of the acquired positions (50), taking into account the measured values (32) acquired in the storage unit (34);and an output unit (38) designed to output the recorded positions (50) with the respective assigned load value (52) or to determine at least one high load value from a total number of determined load values (52) which is greater than the other load values (52) of the total number, and to output the at least one determined high load value with the position (50) assigned to it.