CNC Feed Scheduling Based on Spindle Bending Moments

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Solution Overview

Problem

Milling and grinding processes for complex components often result in inefficient machining due to high safety factors and prolonged processing times, leading to reduced productivity and tool utilization, particularly in aerospace components with stringent accuracy requirements.

Innovation Solution

A feed rate scheduling method that simulates the machining process using engagement geometry and tool path to calculate bending moments, allowing for customized feed rates based on local forces and spindle positions, thereby optimizing the machining process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high safety factors are used in milling and grinding processes, then tool breakage is minimized, but productivity and machine utilization are reduced

Engineering Contradiction:
Improvetool breakage preventionVSAvoidmachining efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic feed rate adjustment by calculating real-time bending moments during machining operations. The feed rate is continuously modified based on the calculated bending moment at each position, allowing the system to operate at higher speeds when safe and reduce speed only when necessary, thereby resolving the contradiction between maintaining reliability and improving productivity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the feed rate parameter dynamically based on calculated bending moments. By computing the bending moment at each position along the tool path and comparing it against threshold values, the system adjusts the feed rate to optimize both tool safety and machining efficiency, moving away from static high safety factors

Inventive Principle:
Principle #35Parameter changes

2Productivity

If complex toolpaths and geometries are machined with minimal modeling, then processing time is reduced, but accuracy and reliability deteriorate

Engineering Contradiction:
Improveprocessing speedVSAvoidmachining accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary calculations of bending moments along the entire tool path before actual machining begins. This advance computation allows the system to identify critical positions where bending moments exceed thresholds, enabling pre-planned feed rate adjustments that ensure accuracy while maintaining efficient processing speeds throughout the operation

Inventive Principle:
Principle #10Preliminary action

3Weight of moving object

If slender components are used to minimize weight, then material efficiency is improved, but process planning complexity and sensitivity increase

Engineering Contradiction:
Improvecomponent weightVSAvoidprocess planning complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The system automatically calculates bending moments and determines optimal feed rates for slender components without requiring complex manual process planning. The automated calculation process accounts for the specific geometry and loading conditions of slender parts, reducing the complexity burden on process planners while enabling efficient machining of weight-optimized components

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4220317B1Bending moment based feed-scheduling in machining
Publication Date: 2025.09.10 RTX CORP
  • EP4220317B1 patent drawingFigure 1
  • EP4220317B1 patent drawingFigure 2
  • EP4220317B1 patent drawingFigure 3A~3C

AI summary

A feed rate scheduling method (200) may comprise: receiving an engagement geometry of a subtractive component (110) for use in a computer numerical control (CNC) machining process; receiving a tool path for forming a component from a workpiece (124) via the CNC machining process; calculating a plurality of bending moments of a spindle (122) at various intervals along the tool path; and determining a feed rate schedule for the tool path of the subtractive component based on the plurality of bending moment.