Machine Tool Feed-Rate Retraction to Prevent Magnesium Fires

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Solution Overview

Problem

The processing of lightweight materials like magnesium in machine tools poses a significant risk of fire due to friction and heat generation, especially when using rotating milling cutters.

Innovation Solution

A procedure for operating a tool and/or production machine involves rotating the spindle and tool, and reducing the defined feed speed of the tool to a point where it no longer touches the workpiece, thereby creating a retreat position to prevent friction and heat buildup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tool remains in contact with the workpiece during machining, then machining continuity is maintained, but friction and heat generation increase causing fire risk

Engineering Contradiction:
Improvefire preventionVSAvoidmachining continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The control system proactively monitors feed rate parameters and predicts potential fire risks before they occur. When the feed rate falls below the threshold, the system automatically triggers tool retraction in advance, preventing the accumulation of dangerous heat levels rather than reacting after fire hazards have materialized.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the actual feed rate during machining operations and compares it against the predetermined safe threshold. This real-time feedback mechanism enables the control system to detect when the tool is moving too slowly relative to spindle rotation, automatically triggering retraction commands to eliminate fire risks caused by excessive friction and heat generation.

Inventive Principle:
Principle #23Feedback

2Reliability

If the feed rate is reduced to improve safety, then fire risk decreases, but machining efficiency deteriorates

Engineering Contradiction:
Improvefire safetyVSAvoidmachining efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the tool's motion state based on real-time feed rate conditions. Rather than maintaining a constantly reduced feed rate, the tool operates at normal high-speed feed rates when safety conditions are met, and only transitions to retraction mode when the feed rate falls below the safety threshold, thereby maintaining high machining efficiency while ensuring safety.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of the tool by transitioning from a low feed rate state to a retraction state when safety thresholds are violated. This parameter change eliminates the need to permanently operate at reduced feed rates, allowing the system to maintain both high machining efficiency during normal operation and fire safety when feed rate anomalies occur.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the tool is continuously retracted to prevent fire, then fire risk is eliminated, but tool wear increases due to repeated engagement and disengagement

Engineering Contradiction:
Improvefire preventionVSAvoidtool lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The system applies tool retraction only partially and selectively - specifically when the feed rate falls below the safety threshold - rather than continuously retracting the tool throughout the entire machining process. This partial application of the safety measure eliminates unnecessary retraction cycles, reducing tool wear from repeated engagement and disengagement while maintaining fire prevention effectiveness.

Inventive Principle:
Principle #16Partial or excessive action

4Reliability

If coolant is used to reduce heat, then fire risk decreases, but system complexity and cost increase

Engineering Contradiction:
Improvefire preventionVSAvoidcoolant system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the need for complex coolant systems by implementing a feed rate-monitored automatic retraction mechanism. Instead of relying on external coolant delivery systems to manage heat, the control system directly prevents heat generation by retracting the tool when feed rate conditions indicate potential fire risks, thereby simplifying the overall machining system.

Inventive Principle:
Principle #2Taking out (Extraction)

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

This approach effectively prevents fires during machining by maintaining a safe distance between the tool and workpiece, reducing wear on the tool, and simplifying the processing of flammable materials without the need for extensive coolant or adjustments to the machining parameters.

Implementation Method 1

The cutter then rubs against the workpiece, generating a lot of heat and potentially causing a fire

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4338018B1Method for operating a machine tool and/or production machine
Publication Date: 2025.04.02 SIEMENS AG
  • EP4338018B1 patent drawingFigure 1~2
  • EP4338018B1 patent drawingFigure 3
  • EP4338018B1 patent drawingFigure 4~5

AI summary

The invention relates to methods for operating a machine tool and/or production machine (1), which has a spindle (5) and a tool (6) for processing a workpiece (8), and in which, when the spindle (5) rotates and a defined speed of advance of the tool (6) is undershot, the tool (6) is moved into a retracted position (R) in such a way that the tool (6) no longer touches the workpiece (8). The invention further relates to a machine tool and/or production machine (1) for carrying out the method, a system (3) and a computer program product (4).