Servo Control Device Spindle Failure Detection

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Solution Overview

Problem

Existing spindle failure detection methods for machine tools require additional sensors and analysis devices, increasing complexity and difficulty in detecting damage to components like bearings, and are not effective in detecting spindle failures using load fluctuation from electrical current values.

Innovation Solution

A servo control device that utilizes feedback signals from the positioning servomotor, including electrical current, velocity, or position, to analyze and detect spindle failures through Fourier transformation and threshold comparisons, without the need for external sensors or analysis devices, and includes a notification and retracting unit to alert and respond to failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sensors and analysis devices are added to detect spindle failure, then detection capability is improved, but device complexity increases

Engineering Contradiction:

Improvespindle failure detection capabilityVSAvoiddevice configuration complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The servo control device utilizes its own existing feedback signals from the positioning servomotor to detect spindle failure, rather than requiring external sensors or analysis devices. The device performs self-diagnosis by analyzing feedback signals it already receives during normal operation, thereby improving detection capability without adding external components.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The feedback signal acquisition and analysis functionality is integrated into the servo control device, allowing it to perform both its primary function of position control and the secondary function of spindle failure detection. This multi-functionality eliminates the need for separate dedicated detection devices, reducing overall system complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If external sensors and analysis devices are installed, then spindle failure detection is enabled, but installation space is required

Engineering Contradiction:

Improvespindle failure detection capabilityVSAvoidinstallation space

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The spindle failure detection function is merged with the existing servo control device. The analysis unit is integrated into the servo control device, combining multiple functions (position control and failure detection) into a single device, thereby eliminating the need for separate installation space for external detection equipment.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The servo control device uses its own internal resources (feedback signal acquisition unit and analysis unit) to perform spindle failure detection, eliminating the need for external sensors and analysis devices that would require additional installation space.

Inventive Principle:

Principle #25Self-service

3Ease of operation

If load fluctuation detection from electrical current is used, then detection simplicity is improved, but detection precision for spindle failure decreases

Engineering Contradiction:

Improvedetection method simplicityVSAvoidspindle failure detection precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The invention utilizes feedback signals from the positioning servomotor, which contain information about the actual position, velocity, and electrical current. By analyzing these feedback signals, the system achieves both simplicity (using existing signals) and precision (through spectral analysis of the feedback data) in detecting spindle failure.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The invention transforms the feedback signal from the time domain to the frequency domain through spectral analysis (Fourier transformation). This parameter transformation allows the detection of specific frequency components characteristic of spindle bearing damage, thereby improving detection precision while maintaining the simplicity of using existing electrical current data.

Inventive Principle:

Principle #35Parameter changes

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 efficient detection of spindle failures within a simple configuration, preventing machining precision decline and defective workpieces by analyzing feedback signals to determine signal intensity thresholds, allowing for timely notification and spindle retraction.

Implementation Method 1

the analysis/detection unit 226 that analyzes the feedback signal acquired to detect failure of the spindle

Methodology Applied

Scientific EffectFourier transformation:

Data Source

PatentUS10493576B2Servo control device, spindle failure detection method using servo control device, and non-transitory computer readable medium encoded with computer program

Publication Date: 2019.12.03 FANUC LTD

AI summary

To provide an arrangement capable of detecting spindle failure in a machine tool using an existing servo control device, without providing separate external sensors, a failure analysis device or the like. A servo control device (22), which detects failure of a spindle of a machine tool including the spindle, a feed shaft, and a positioning servomotor that is installed to the feed shaft and is for deciding the position of the spindle, includes: a feedback acquisition unit (222) that acquires a feedback signal of the positioning servomotor; and an analysis/detection unit 226 that analyzes the feedback signal acquired to detect failure of the spindle.