Main Spindle Failure Detection via Inertia Speed Decay
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Solution Overview
Problem
Existing main spindle failure detection devices for machine tools either require expensive vibration sensors for quick failure detection or are inefficient due to non-linear changes in rotation speed over time, making daily diagnosis challenging and costly.
Innovation Solution
A main spindle failure detection device and method utilizing a rotation speed detection unit, reach time estimation unit, and determining unit, which estimates and compares reach time using a non-linear model, specifically an exponential function, to accurately diagnose failures in a short and cost-effective manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If vibration analysis is used for failure detection, then detection time is short, but device cost becomes expensive
Solution Approach 1:
The patent replaces the mechanical vibration sensor system with an electrical control system that utilizes the existing rotation speed detection means. Instead of measuring physical vibrations, the system detects changes in rotation speed during inertia operation to infer bearing status, thereby eliminating expensive vibration sensors while maintaining fast detection capability
Solution Approach 2:
The patent introduces rotation speed detection as an intermediary parameter to indirectly assess bearing condition. Rather than directly measuring vibration, the system uses rotation speed changes during inertia operation as a mediator to detect bearing failures, achieving cost reduction while preserving detection effectiveness
2Device complexity
If rotation speed change comparison is used for failure diagnosis, then device cost is low, but diagnosis time becomes long
Solution Approach 1:
The patent performs rotation speed measurement only during the brief inertia operation period immediately after power cutoff, rather than continuous monitoring. This partial action approach uses the short-duration inertia phase to gather sufficient diagnostic data, reducing overall diagnosis time while maintaining accuracy
Solution Approach 2:
The patent changes the operational parameter from steady-state rotation to inertia-state rotation. By measuring rotation speed during the transient inertia operation when the spindle coasts to stop, the system captures bearing friction characteristics that are not apparent during normal operation, enabling faster and more accurate diagnosis
3Device complexity
If linear model is used for reach time estimation, then calculation is simple, but estimation accuracy becomes low
Solution Approach 1:
The patent transitions from a static linear model to a dynamic non-linear model for reach time estimation. The non-linear model adapts to the changing friction characteristics of the bearing during inertia operation, accurately capturing the non-uniform deceleration behavior that linear models cannot represent, thereby improving estimation accuracy
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 accurate and rapid failure determination of the main spindle on a daily basis, improving diagnosis accuracy and preventing accidental machine stoppages by using a non-linear model to estimate the time for the main spindle's rotation speed to reach a threshold, and further validating with actual measurements.
Implementation Method 1
a start rotation speed before the power of a main spindle driving device is cut off and a rotation speed during an inertia operation
Data Source
AI summary
A main spindle failure detection device for a machine tool includes a rotation speed detection unit, a reach time estimation unit, and a determining unit. The reach time estimation unit is configured to estimate a reach time in which the rotation speed of the main spindle reaches a predetermined rotation speed threshold using a non-linear model based on a rotation speed of the main spindle detected at a start of an inertia operation and a rotation speed of the main spindle detected after an elapse of preset measurement time from the start of the inertia operation. The determining unit is configured to compare the reach time estimated by the reach time estimation unit with a preset reach time in which the rotation speed reaches the rotation speed threshold, so as to determine a failure in the main spindle based on a result of the comparison.