Machine Tool Current Monitoring for Per-Tool Wear Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing technologies face challenges in detecting tool abnormalities in machine tools that use multiple tools without requiring external device connections to the NC machine, making it difficult to determine optimal tool replacement cycles and detect malfunctions in actual production settings.

Innovation Solution

A current measuring system that employs two current sensors connected to an information processing device, synchronizing time-history waveforms of currents from a motor receiving load fluctuations and a motor changing tools to analyze and detect abnormalities based on current values for each tool, allowing for real-time monitoring and prediction of tool wear and malfunctions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequency information from acceleration sensors is used to detect tool wear, then tool wear detection is achieved, but the technology cannot be applied to current sensor data and requires external device connections

Engineering Contradiction:

Improvetool wear detection accuracyVSAvoidsensor type and connection requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical vibration-based detection system (acceleration sensors) with an electrical current-based detection system. By analyzing current fluctuations from motors during tool operation, the system achieves tool wear detection without requiring mechanical vibration sensors or external device connections to the NC machine, thus substituting a mechanical measurement approach with an electrical one.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system utilizes the existing motor current data that is already being collected during normal machine operation for tool wear detection purposes. Instead of requiring separate acceleration sensors and external analysis devices, the current measuring system extracts tool condition information from the motor's own current consumption patterns, allowing the motor's operational data to serve multiple functions including wear detection.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If tool wear detection is performed using conventional methods, then single-tool processing can be monitored, but multi-tool processing cannot be individually analyzed

Engineering Contradiction:

Improvetool wear detection capabilityVSAvoidmulti-tool processing compatibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent segments the tool change process into distinct phases by identifying specific current patterns in the motor current data. By detecting tool change signals through current waveform analysis and separating the operational data into individual tool segments, the system can independently analyze and monitor wear for each tool in a multi-tool processing sequence, enabling individual tool assessment rather than aggregate monitoring.

Inventive Principle:

Principle #1Segmentation

3Reliability

If external devices are connected to NC machines for tool monitoring, then tool abnormality detection is enabled, but machine tool reconstruction occurs which manufacturers discourage

Engineering Contradiction:

Improvetool abnormality detectionVSAvoidsystem integration requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent makes the motor current measurement system serve multiple functions: it continues to monitor motor operation as before, and simultaneously provides tool wear detection and abnormality monitoring capabilities. By extracting multiple types of information from the same current data source, the system achieves tool monitoring without adding separate sensors or external devices, thus avoiding machine reconstruction while maintaining reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11913992B2Current measuring system for machine tool and current measuring method thereof

Publication Date: 2024.02.27 MAZIN INC

AI summary

A machine tool includes a first motor that receives load fluctuation when the workpiece is processed and a second motor that operates to change the plural kinds of tools. An information processing device takes out the current of the first motor measured by the first current sensor for each signal that occurs at the changing operation of the plural kinds of tools and is measured by the second current sensor, and relatively compares a non-negative function value that has a current value at each taken-out segment as a parameter for each number of times of processing on the workpiece, thereby detecting a tool abnormality for each kind of the tool.