Machine Tool Collision Detection Using Load and Interference Zones
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Solution Overview
Problem
Existing machine tool abnormality detection methods fail to effectively prevent collisions between tools and works or jigs, leading to excessive load on spindles and feed axes, especially when incorrect or damaged shape data is used, resulting in potential deterioration or destruction of components.
Innovation Solution
A controller-based abnormality detection device that monitors load, determines machining state, calculates interfering areas using stored shape data, and compares tool positions to detect abnormalities, preventing collisions by alerting operators before damage occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a method of storing work shape data and tool shape data in advance and limiting the movable range of the feed axis is used to prevent interference, then interference between tool and work can be prevented under normal conditions, but the system fails to detect abnormalities such as wrong shape data input, wrong position attachment, or destroyed tools, leading to potential collisions and component deterioration
Solution Approach 1:
The system pre-calculates the interfering area between tool and work based on stored shape data before machining begins. This preliminary action creates a reference zone that will be used for real-time comparison during machining, enabling abnormality detection without adding complex real-time calculation systems.
Solution Approach 2:
The system continuously monitors the actual tool position during machining and compares it with the pre-calculated interfering area. When the tool position deviates from the expected non-interfering zone, the system generates an abnormality signal. This feedback mechanism enables reliable abnormality detection using a relatively simple comparison process.
2Object-affected harmful factors
If load monitoring is used to detect abnormalities when load exceeds threshold, then collisions can be detected immediately and machine can be stopped to prevent component deterioration, but the system cannot prevent collisions from occurring in the first place when wrong shape data is used
Solution Approach 1:
The interfering area is calculated in advance based on tool and work shape data, creating a predictive safety zone before machining begins. This allows the system to identify potential collision risks before they occur, rather than waiting for load increases to detect problems.
Solution Approach 2:
The interfering area calculation acts as an intermediary between the tool position and the collision detection. Instead of directly monitoring for collisions through load sensing, the system uses the pre-calculated interfering area as a reference to predict and prevent collisions before they occur.
3Adaptability or versatility
If the movable range of the feed axis is limited to prevent interference, then tool and work interference can be avoided, but the system cannot adapt when actual tool or work positions differ from stored shape data, resulting in undetected collisions
Solution Approach 1:
The system continuously compares actual tool position during machining with the pre-calculated interfering area. This feedback loop automatically adapts to actual positions and detects deviations, providing abnormality detection capability without requiring complex manual adjustments or procedures.
Solution Approach 2:
The system automatically detects abnormalities by comparing real-time tool position with the pre-calculated interfering area. No manual intervention or complex configuration is needed - the system self-adjusts and self-detects based on the stored shape data and actual machining conditions.
Data Source
AI summary
An abnormality detection device of a machine tool including a spindle and a feed axis and includes: a load monitoring unit that monitors a load of the spindle or the feed axis; a machining state determination unit that determines that the machine tool is in a machining state when the load of the spindle or the feed axis is equal to or larger than a threshold; a storage unit that stores shape data of the work and shape data of the tool in advance; an interfering area calculation unit that calculates an interfering area in which the tool interferes with the work based on the shape data of the work and the shape data of the tool; and an abnormality detection unit that detects an abnormality in the machine tool by comparing a position of the tool in relation to the work when it is determined that the machine tool is in the machining state with the calculated interfering area.